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 A270957 #5 Mar 27 2016 14:26:37 %S A270957 1,21,197,1421,9573,64724,449567,3230230,24053169,185658621, %T A270957 1484943532,12299106220,105400873263,933717036862,8541991253431, %U A270957 80620086997245,784225175253212,7854824886117957,80933906884404094,857116366195307414,9321782438290435408 %N A270957 Number of set partitions of [n] having exactly three pairs (m,m+1) such that m+1 is in some block b and m is in block b+1. %H A270957 Alois P. Heinz, <a href="/A270957/b270957.txt">Table of n, a(n) for n = 6..220</a> %H A270957 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %e A270957 a(6) = 1: 136|25|4. %e A270957 a(7) = 21: 1247|36|5, 1347|26|5, 1357|246, 135|247|6, 137|246|5, 1367|25|4, 136|257|4, 136|25|47, 136|25|4|7, 137|256|4, 13|257|46, 13|25|47|6, 137|26|45, 13|27|46|5, 147|236|5, 157|246|3, 15|247|36, 15|24|37|6, 17|246|35, 1|247|36|5, 17|26|35|4. %Y A270957 Column k=3 of A270953. %K A270957 nonn %O A270957 6,2 %A A270957 _Alois P. Heinz_, Mar 26 2016