238 (two hundred [and] thirty-eight) is the natural number following 237 and preceding 239.

In mathematics

← 237 238 239 →
Cardinaltwo hundred thirty-eight
Ordinal238th
(two hundred thirty-eighth)
Factorization2 × 7 × 17
Primeno
Greek numeralΣΛΗ´
Roman numeralCCXXXVIII
Binary111011102
Ternary222113
Senary10346
Octal3568
Duodecimal17A12
HexadecimalEE16

238 is an untouchable number.[1] There are 238 2-vertex-connected graphs on five labeled vertices,[2] and 238 order-5 polydiamonds (polyiamonds that can partitioned into 5 diamonds).[3] Out of the 720 permutations of six elements, exactly 238 of them have a unique longest increasing subsequence.[4]

There are 238 compact and paracompact hyperbolic groups of ranks 3 through 10.[5]

References

  1. ^ Sloane, N. J. A. (ed.). "Sequence A005114 (Untouchable numbers: impossible values for sum of aliquot parts of n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A013922 (Number of labeled connected graphs with n nodes and 0 cutpoints (blocks or nonseparable graphs))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ Sloane, N. J. A. (ed.). "Sequence A056844 (Number of polydiamonds: polyominoes made from n diamonds)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  4. ^ Sloane, N. J. A. (ed.). "Sequence A167995 (Total number of permutations on {1,2,...,n} that have a unique longest increasing subsequence)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  5. ^ Carbone, Lisa; Chung, Sjuvon; Cobbs, Leigh; Mcrae, Robert; Nandi, Debajyoti; Navqi, Yusra; Penta, Diego (March 2010). "Classification of hyperbolic Dynkin diagrams, root lengths and Weyl group orbits" (PDF). Journal of Physics A: Mathematical and Theoretical. 43 (15): 30. arXiv:1003.0564. Bibcode:2010JPhA...43o5209C. doi:10.1088/1751-8113/43/15/155209. MR 2608277. S2CID 16946456. Retrieved 2022-11-01.
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