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.
%I A159121 #4 Feb 16 2025 08:33:10
%S A159121 1,37,893,18156,341049,6184359,110865138,1992632288,36228489065,
%T A159121 670284655152
%N A159121 Number of permutations of 1..n containing the relative rank sequence { 146523 } at any spacing.
%C A159121 Same series for 342651 435126 156243 621534 325641 452136 631254
%H A159121 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PermutationPattern.html">Permutation Pattern</a>
%Y A159121 A056986 A158005 A158423
%K A159121 nonn
%O A159121 6,2
%A A159121 _R. H. Hardin_ Apr 05 2009