A324066 Number of defective (binary) heaps on n elements where five ancestor-successor pairs do not have the correct order.

0, 0, 0, 0, 0, 16, 120, 720, 4830, 31360, 211680, 1555200, 11880000, 95293440, 815443200, 7687680000, 60432372000, 530552422400, 4945330790400, 51912327168000, 496766020608000, 5425624055808000, 61093281300480000, 781258429366272000, 8157685988035584000

Offset: 0

Author

Alois P. Heinz, Feb 13 2019

Keywords

• nonn

Comments

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)).

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..200
• Eric Weisstein's World of Mathematics, Heap
• Wikipedia, Binary heap
• Wikipedia, Permutation

Crossrefs

Column k=5 of A306393.

Cf. A056971.