238 (two hundred
ndthirty-eight) is the
natural number following
237 and preceding
239
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Year 239 ( CCXXXIX) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Gordianus and Aviola (or, less frequently, year 992 ''A ...
.
In mathematics
238 is an
untouchable number
An untouchable number is a positive integer that cannot be expressed as the sum of all the proper divisors of any positive integer (including the untouchable number itself). That is, these numbers are not in the image of the aliquot sum function. ...
.
There are 238
2-vertex-connected graphs on five labeled vertices, and 238 order-5 polydiamonds (
polyiamonds that can partitioned into 5 diamonds). Out of the 720 permutations of six elements, exactly 238 of them have a unique
longest increasing subsequence.
There are 238
compact and paracompact hyperbolic groups of
ranks 3 through 10.
References
Integers
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