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 A286433 #4 May 09 2017 19:03:22 %S A286433 1,6,25,98,399,1746,8271,42284,231939,1357128,8427181,55288860, %T A286433 381798629,2765917074,20960284277,165729739590,1364153612299, %U A286433 11665484410094,103448316470723,949739632313480,9013431476894623,88304011710168668,891917738589610553 %N A286433 Number of entries in the second last blocks of all set partitions of [n]. %H A286433 Alois P. Heinz, <a href="/A286433/b286433.txt">Table of n, a(n) for n = 2..250</a> %H A286433 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %e A286433 a(3) = 6 because the number of entries in the second last blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 0+2+2+1+1 = 6. %Y A286433 Column k=2 of A286416. %K A286433 nonn %O A286433 2,2 %A A286433 _Alois P. Heinz_, May 09 2017