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A324067
Number of defective (binary) heaps on n elements where six ancestor-successor pairs do not have the correct order.
2
0, 0, 0, 0, 0, 8, 100, 720, 5040, 36736, 268800, 2073600, 17186400, 147502080, 1331616000, 13047091200, 110053944000, 1011903692800, 9874978713600, 106953080832000, 1086116967936000, 12275238666240000, 144074916311040000, 1890064025321472000
OFFSET
0,6
COMMENTS
Or number of permutations p of [n] having exactly six 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=6 of A306393.
Cf. A056971.
Sequence in context: A367445 A316870 A181034 * A083227 A261742 A222486
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 13 2019
STATUS
approved