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 A323961 Number of defective (binary) heaps on n elements with exactly five defects. 2
 0, 20, 360, 5922, 82880, 1017060, 11165280, 123760560, 1310267904, 14197154400, 153775564800, 1646888944800, 18660402342400, 201542310930240, 2419644394552320, 26818494698361600, 342175409500446720, 3913572812111424000, 53353484649907200000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 5,2 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. Sequence in context: A285393 A156455 A089350 * A004292 A053508 A060918 Adjacent sequences:  A323958 A323959 A323960 * A323962 A323963 A323964 KEYWORD nonn AUTHOR Alois P. Heinz, Feb 09 2019 STATUS approved

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Last modified January 18 14:07 EST 2021. Contains 340254 sequences. (Running on oeis4.)