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A323961
Number of defective (binary) heaps on n elements with exactly five defects.
2
0, 20, 360, 5922, 82880, 1017060, 11165280, 123760560, 1310267904, 14197154400, 153775564800, 1646888944800, 18660402342400, 201542310930240, 2419644394552320, 26818494698361600, 342175409500446720, 3913572812111424000, 53353484649907200000
OFFSET
5,2
COMMENTS
Or number of permutations p of [n] having exactly five indices i in {1,...,n} such that p(i) > p(floor(i/2)).
LINKS
Eric Weisstein's World of Mathematics, Heap
Wikipedia, Binary heap
CROSSREFS
Column k=5 of A306343.
Cf. A056971.
Sequence in context: A156455 A358365 A089350 * A004292 A053508 A060918
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 09 2019
STATUS
approved