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

Author

Alois P. Heinz, Feb 09 2019

Keywords

• nonn

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.