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 A324065 #7 Feb 16 2025 08:33:57
%S A324065 0,0,0,0,3,24,120,720,4200,24192,151200,1056000,7286400,54743040,
%T A324065 442041600,3997593600,29081052000,244365721600,2164235673600,
%U A324065 21996748800000,197620929792000,2090405560320000,22475789107200000,280198170869760000,2772753817946112000
%N A324065 Number of defective (binary) heaps on n elements where four ancestor-successor pairs do not have the correct order.
%C A324065 Or number of permutations p of [n] having exactly four pairs (i,j) in {1,...,n} X {1,...,floor(log_2(i))} such that p(i) > p(floor(i/2^j)).
%H A324065 Alois P. Heinz, <a href="/A324065/b324065.txt">Table of n, a(n) for n = 0..200</a>
%H A324065 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Heap.html">Heap</a>
%H A324065 Wikipedia, <a href="https://en.wikipedia.org/wiki/Binary_heap">Binary heap</a>
%H A324065 Wikipedia, <a href="https://en.wikipedia.org/wiki/Permutation">Permutation</a>
%Y A324065 Column k=4 of A306393.
%Y A324065 Cf. A056971.
%K A324065 nonn
%O A324065 0,5
%A A324065 _Alois P. Heinz_, Feb 13 2019