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A324068
Number of defective (binary) heaps on n elements where seven ancestor-successor pairs do not have the correct order.
2
0, 0, 0, 0, 0, 0, 60, 640, 5040, 39424, 315840, 2572800, 22730400, 207820800, 1979577600, 20119756800, 180756576000, 1740900761600, 17732095180800, 197872975872000, 2123068147200000, 24858537099264000, 303091124244480000, 4076808466857984000
OFFSET
0,7
COMMENTS
Or number of permutations p of [n] having exactly seven pairs (i,j) in {1,...,n} X {1,...,floor(log_2(i))} such that p(i) > p(floor(i/2^j)).
LINKS
Eric Weisstein's World of Mathematics, Heap
Wikipedia, Binary heap
Wikipedia, Permutation
CROSSREFS
Column k=7 of A306393.
Cf. A056971.
Sequence in context: A081384 A283786 A099344 * A223242 A244837 A268624
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 13 2019
STATUS
approved