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 A324069 #7 Feb 16 2025 08:33:57
%S A324069 0,0,0,0,0,0,20,480,4830,40320,346080,3014400,28036800,271180800,
%T A324069 2723635200,28751923200,273405132000,2754444492800,29222409216000,
%U A324069 335670386688000,3786723502848000,45941770321920000,580488335032320000,8000481890598912000
%N A324069 Number of defective (binary) heaps on n elements where eight ancestor-successor pairs do not have the correct order.
%C A324069 Or number of permutations p of [n] having exactly eight pairs (i,j) in {1,...,n} X {1,...,floor(log_2(i))} such that p(i) > p(floor(i/2^j)).
%H A324069 Alois P. Heinz, <a href="/A324069/b324069.txt">Table of n, a(n) for n = 0..200</a>
%H A324069 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Heap.html">Heap</a>
%H A324069 Wikipedia, <a href="https://en.wikipedia.org/wiki/Binary_heap">Binary heap</a>
%H A324069 Wikipedia, <a href="https://en.wikipedia.org/wiki/Permutation">Permutation</a>
%Y A324069 Column k=8 of A306393.
%Y A324069 Cf. A056971.
%K A324069 nonn
%O A324069 0,7
%A A324069 _Alois P. Heinz_, Feb 13 2019