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 A178009 #14 May 28 2016 10:22:39 %S A178009 1,1,1,2,6,24,60,240,1260,8064,36288,241920,1995840,19160064, %T A178009 124540416,1162377216,13076743680,167382319104,1422749712384, %U A178009 17072996548608,243290200817664,3892643213082624,34060628114472960,428190753439088640,6463004184721244160 %N A178009 Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/4)] (4-way heap). %H A178009 Alois P. Heinz, <a href="/A178009/b178009.txt">Table of n, a(n) for n = 0..491</a> %H A178009 Wikipedia, <a href="https://en.wikipedia.org/wiki/D-ary_heap">D-ary heap</a> %Y A178009 Simple 2-way heap A056971. %Y A178009 Column k=4 of A273693. %K A178009 nonn %O A178009 0,4 %A A178009 _R. H. Hardin_, May 17 2010 %E A178009 a(0), a(20)-a(24) from _Alois P. Heinz_, May 27 2016