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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A273755 Number of binary min heaps on [n] that give a max heap when reversed.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 5, 11, 26, 55, 214, 547, 1802, 6579, 22446, 77170, 401150, 1509788, 7198829, 36540168
Offset: 0

Views

Author

Alois P. Heinz, May 29 2016

Keywords

Comments

Or number of binary max heaps on [n] that give a min heap when reversed.

Examples

			a(4) = 2: 1234, 1324.
a(5) = 3: 12345, 12435, 13245.
a(6) = 5: 123456, 123546, 124356, 132456, 132546.
a(7) = 11: 1234567, 1234657, 1235467, 1243567, 1243657, 1245367, 1253467, 1254367, 1324567, 1324657, 1325467.

Links

Crossrefs

Cf. A056971, A273754.
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