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 A324066 #7 Feb 16 2025 08:33:57
%S A324066 0,0,0,0,0,16,120,720,4830,31360,211680,1555200,11880000,95293440,
%T A324066 815443200,7687680000,60432372000,530552422400,4945330790400,
%U A324066 51912327168000,496766020608000,5425624055808000,61093281300480000,781258429366272000,8157685988035584000
%N A324066 Number of defective (binary) heaps on n elements where five ancestor-successor pairs do not have the correct order.
%C A324066 Or number of permutations p of [n] having exactly five pairs (i,j) in {1,...,n} X {1,...,floor(log_2(i))} such that p(i) > p(floor(i/2^j)).
%H A324066 Alois P. Heinz, <a href="/A324066/b324066.txt">Table of n, a(n) for n = 0..200</a>
%H A324066 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Heap.html">Heap</a>
%H A324066 Wikipedia, <a href="https://en.wikipedia.org/wiki/Binary_heap">Binary heap</a>
%H A324066 Wikipedia, <a href="https://en.wikipedia.org/wiki/Permutation">Permutation</a>
%Y A324066 Column k=5 of A306393.
%Y A324066 Cf. A056971.
%K A324066 nonn
%O A324066 0,6
%A A324066 _Alois P. Heinz_, Feb 13 2019