A323963 - OEIS

%I #6 Feb 09 2019 21:21:59

%S 0,210,7616,185460,4200960,77887920,1310267904,21025461600,

%T 314958758400,4765553385120,69086614338560,1013373907056960,

%U 14714554645140480,212868974122848000,3168605413206097920,45787509175434048000,705241846739554713600,10297540417675899801600

%N Number of defective (binary) heaps on n elements with exactly seven defects.

%C Or number of permutations p of [n] having exactly seven indices i in {1,...,n} such that p(i) > p(floor(i/2)).

%H Alois P. Heinz, <a href="/A323963/b323963.txt">Table of n, a(n) for n = 7..200</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Heap.html">Heap</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Binary_heap">Binary heap</a>

%Y Column k=7 of A306343.

%Y Cf. A056971.

%K nonn

%O 7,2

%A _Alois P. Heinz_, Feb 09 2019