cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A372181 a(n) is the smallest number whose symmetric representation of sigma consists of n copies of unimodal pattern 121 (separated by 0's if n > 1).

Original entry on oeis.org

6, 78, 1014, 12246, 171366, 1922622, 28960854, 300014754, 4174476774
Offset: 1

Views

Author

Hartmut F. W. Hoft, Apr 21 2024

Keywords

Comments

This sequence is infinite (see A372180).

Examples

			a(2) = 78 is the smallest number whose symmetric representations of sigma has unimodal pattern 1210121.
a(4) = 12246 is the smallest number whose symmetric representations of sigma has unimodal pattern 121012101210121.
		

Crossrefs

Row 2 of A367377.
Row 1 of A372180.
Cf. A237593.

Programs

  • Mathematica
    (* function seqQ[ ] is defined in A372180 *)
    smallest[s_, m_] := NestWhile[#+1&, s, !seqQ[#, m]&]
    a372181[n_] := Rest[FoldList[smallest[#1, #2]&, 1, Range[n]]]
    a372181[9] (* long computation time *)