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A324066
Number of defective (binary) heaps on n elements where five ancestor-successor pairs do not have the correct order.
2
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
0,6
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
Eric Weisstein's World of Mathematics, Heap
Wikipedia, Binary heap
Wikipedia, Permutation
CROSSREFS
Column k=5 of A306393.
Cf. A056971.
Sequence in context: A374014 A014805 A022611 * A164542 A351383 A027049
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 13 2019
STATUS
approved