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259 (number)
259 (two hundred ndfifty-nine) is the natural number following 258 and preceding 260. In mathematics 259 is: *a semiprime *63 + 62 + 6 + 1, so 259 is a repdigit in base 6 (11116) *a lucky number In other fields *259 is the country code of Zanzibar Zanzibar (; ; ) is an insular semi-autonomous province which united with Tanganyika in 1964 to form the United Republic of Tanzania. It is an archipelago in the Indian Ocean, off the coast of the mainland, and consists of many small islan .... References {{Integers, 2 Integers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country"). Numbers used for counting are called ''Cardinal number, cardinal numbers'', and numbers used for ordering are called ''Ordinal number, ordinal numbers''. Natural numbers are sometimes used as labels, known as ''nominal numbers'', having none of the properties of numbers in a mathematical sense (e.g. sports Number (sports), jersey numbers). Some definitions, including the standard ISO/IEC 80000, ISO 80000-2, begin the natural numbers with , corresponding to the non-negative integers , whereas others start with , corresponding to the positive integers Texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, while in other writings, that term is used instead for the integers (including negative integers). The natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
258 (number)
258 (two hundred ndfifty-eight) is the natural number following 257 and preceding 259. In mathematics 258 is: *a sphenic number *a nontotient *the sum of four consecutive prime numbers because 258 = 59 + 61 + 67 + 71 *63 + 62 + 6 *an Ulam number In mathematics, the Ulam numbers comprise an integer sequence devised by and named after Stanislaw Ulam, who introduced it in 1964. The standard Ulam sequence (the (1, 2)-Ulam sequence) starts with ''U''1 = 1 and ''U''2 =&nbs ... References {{Integers, 2 Integers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
260 (number)
260 (two hundred ndsixty) is the natural number following 259 and preceding 261. It is also the magic constant of the ''n''×''n'' normal magic square and ''n''-queens problem for ''n'' = 8, the size of an actual chess board. 260 is also the magic constant of the Franklin magic square devised by Benjamin Franklin. The minor diagonal gives 260, and in addition a number of combinations of two half diagonals of four numbers from a corner to the center give 260. There are 260 days in the Mayan sacred calendar Tzolkin. 260 may also refer to the years AD 260 and 260 BC. Integers from 261 to 269 261 261 = 32·29, lucky number, nonagonal number, unique period in base 2, number of possible unfolded tesseract patterns. 262 262 = 2·131, meandric number, open meandric number, untouchable number, happy number, palindrome number, semiprime, current first uninteresting number (by Alex Bellos's definition). 263 263 is a prime, safe prime, hap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiprime
In mathematics, a semiprime is a natural number that is the product of exactly two prime numbers. The two primes in the product may equal each other, so the semiprimes include the squares of prime numbers. Because there are infinitely many prime numbers, there are also infinitely many semiprimes. Semiprimes are also called biprimes. Examples and variations The semiprimes less than 100 are: Semiprimes that are not square numbers are called discrete, distinct, or squarefree semiprimes: The semiprimes are the case k=2 of the k-almost primes, numbers with exactly k prime factors. However some sources use "semiprime" to refer to a larger set of numbers, the numbers with at most two prime factors (including unit (1), primes, and semiprimes). These are: Formula for number of semiprimes A semiprime counting formula was discovered by E. Noel and G. Panos in 2005. Let \pi_2(n) denote the number of semiprimes less than or equal to n. Then \pi_2(n) = \sum_^ pi(n/p_k) - k + 1 /math> where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repdigit
In recreational mathematics, a repdigit or sometimes monodigit is a natural number composed of repeated instances of the same digit in a positional number system (often implicitly decimal). The word is a portmanteau of repeated and digit. Examples are 11, 666, 4444, and 999999. All repdigits are palindromic numbers and are multiples of repunits. Other well-known repdigits include the repunit primes and in particular the Mersenne primes (which are repdigits when represented in binary). Repdigits are the representation in base B of the number x\frac where 0 1 and ''n'', ''m'' > 2 : **(''p'', ''x'', ''y'', ''m'', ''n'') = (31, 5, 2, 3, 5) corresponding to 31 = 111112 = 1115, and, **(''p'', ''x'', ''y'', ''m'', ''n'') = (8191, 90, 2, 3, 13) corresponding to 8191 = 11111111111112 = 11190, with 11111111111 is the repunit with thirteen digits 1. *For each sequence of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucky Number
In number theory, a lucky number is a natural number in a set which is generated by a certain "sieve". This sieve is similar to the Sieve of Eratosthenes that generates the primes, but it eliminates numbers based on their position in the remaining set, instead of their value (or position in the initial set of natural numbers). The term was introduced in 1956 in a paper by Gardiner, Lazarus, Metropolis and Ulam. They suggest also calling its defining sieve, "the sieve of Josephus Flavius" because of its similarity with the counting-out game in the Josephus problem. Lucky numbers share some properties with primes, such as asymptotic behaviour according to the prime number theorem; also, a version of Goldbach's conjecture has been extended to them. There are infinitely many lucky numbers. Twin lucky numbers and twin primes also appear to occur with similar frequency. However, if ''L''''n'' denotes the ''n''-th lucky number, and ''p''''n'' the ''n''-th prime, then ''L''''n'' > ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zanzibar
Zanzibar (; ; ) is an insular semi-autonomous province which united with Tanganyika in 1964 to form the United Republic of Tanzania. It is an archipelago in the Indian Ocean, off the coast of the mainland, and consists of many small islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. The capital is Zanzibar City, located on the island of Unguja. Its historic centre, Stone Town, is a World Heritage Site. Zanzibar's main industries are spices, raffia and tourism. In particular, the islands produce cloves, nutmeg, cinnamon, and black pepper. For this reason, the Zanzibar Archipelago, together with Tanzania's Mafia Island, are sometimes referred to locally as the "Spice Islands". Tourism in Zanzibar is a more recent activity, driven by government promotion that caused an increase from 19,000 tourists in 1985, to 376,000 in 2016. The islands are accessible via 5 ports and the Abeid Amani Karume International Airport, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
