A379272 Number of binary min-heaps on n elements from the set {0,1} that give a max-heap when reversed.

1, 2, 3, 4, 6, 8, 10, 14, 18, 22, 33, 40, 54, 74, 93, 116, 172, 204, 268, 378, 482, 584, 905, 1036, 1378, 1858, 2520, 3002, 4700, 5298, 7089, 9456, 12420, 15452, 24160, 26542, 36646, 47634, 64183, 75568, 126118, 135226, 188098, 244172, 329098, 383142, 626452, 689466, 980284, 1229296, 1691506

Offset: 0

Author

Alois P. Heinz, Feb 18 2025

Keywords

• nonn

Comments

If n is odd then a(n) is even.

Examples

			a(5) = 8: 00000, 00001, 00011, 00101, 00111, 01011, 01111, 11111.
a(6) = 10: 000000, 000001, 000011, 000101, 000111, 001011, 001111, 010111, 011111, 111111. Min-heaps on 6 elements from the set {0,1} that do not give a max-heap when reversed are: 000010, 000100, 000110, 001001, 001101, 010110.
a(7) = 14: 0000000, 0000001, 0000011, 0000101, 0000111, 0001011, 0001111, 0010011, 0010111, 0011011, 0011111, 0101111, 0111111, 1111111.
		

Links

• Eric Weisstein's World of Mathematics, Heap
• Wikipedia, Binary heap

Crossrefs

Cf. A056971, A091980, A273755.