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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 (list; graph; refs; listen; history; text; internal format)
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

Alois P. Heinz, Table of n, a(n) for n = 5..200

Eric Weisstein's World of Mathematics, Heap

Wikipedia, Binary heap

CROSSREFS

Column k=5 of A306343.

Cf. A056971.

Sequence in context: A285393 A156455 A089350 * A004292 A053508 A060918

Adjacent sequences:  A323958 A323959 A323960 * A323962 A323963 A323964

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Feb 09 2019

STATUS

approved

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Last modified December 2 07:33 EST 2021. Contains 349437 sequences. (Running on oeis4.)