A326505 Number of (binary) max-heaps on n elements from the set {0,1} containing exactly four 0's.

1, 1, 2, 5, 7, 11, 17, 27, 34, 50, 65, 94, 110, 154, 182, 250, 279, 375, 420, 555, 601, 781, 847, 1085, 1152, 1456, 1547, 1932, 2024, 2500, 2620, 3204, 3325, 4029, 4182, 5025, 5179, 6175, 6365, 7535, 7726, 9086, 9317, 10890, 11122, 12926, 13202, 15262, 15539

Offset: 4

Author

Alois P. Heinz, Jul 09 2019

Keywords

• nonn
• easy

Links

• Alois P. Heinz, Table of n, a(n) for n = 4..10000
• Eric Weisstein's World of Mathematics, Heap
• Wikipedia, Binary heap
• Index entries for linear recurrences with constant coefficients, signature (1,2,-2,1,-1,-4,4,1,-1,2,-2,-1,1).

Crossrefs

Column k=4 of A309049.

Formula

G.f.: -x^4*(2*x^3-x^2+1)*(2*x^6-x^5-x^4+x^3+1)/((x^2+1)^2*(x+1)^4*(x-1)^5).