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 A272434 #5 May 01 2016 17:20:27
%S A272434 1,1,1,7,9,31,403,757,2873,12607,333051,761377,3699435,16383121,
%T A272434 108710085,4855474267,13594184793,76375572751,388660153867,
%U A272434 2504206435681,20148774553859,1556349601444477,5050276538344665,33326552998257031,186169293932977115,1305062351972825281,9600936552132048553,106019265737746665727,12708226588208611056333,98137877588880676995127
%N A272434 Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its six immediate predecessors.
%H A272434 Alois P. Heinz, <a href="/A272434/b272434.txt">Table of n, a(n) for n = 0..50</a>
%Y A272434 Column k=6 of A261959.
%K A272434 nonn
%O A272434 0,4
%A A272434 _Alois P. Heinz_, Apr 29 2016