A323961 Number of defective (binary) heaps on n elements with exactly five defects.

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

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: A156455 A358365 A089350 * A004292 A053508 A060918

Adjacent sequences: A323958 A323959 A323960 * A323962 A323963 A323964

Keyword

nonn

Author

Alois P. Heinz, Feb 09 2019

Status

approved