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 A306535 Number of permutations p of [2n] having no index i with |p(i)-i| = n. 4
 1, 1, 9, 265, 14833, 1334961, 176214841, 32071101049, 7697064251745, 2355301661033953, 895014631192902121, 413496759611120779881, 228250211305338670494289, 148362637348470135821287825, 112162153835443422680893595673, 97581073836835777732377428235481 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Also 0th term of the 2n-th forward differences of n!. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..225 Wikipedia, Permutation FORMULA a(n) = A306512(2n,n). a(n) = (2n)! - A306675(n). MAPLE b:= proc(n, k) b(n, k):= `if`(k=0, n!, b(n+1, k-1) -b(n, k-1)) end: a:= n-> b(0, 2*n): seq(a(n), n=0..23); CROSSREFS Cf. A306512, A306675. Cf. A000142, A047920, A068106. Sequence in context: A081059 A202884 A188963 * A144684 A191960 A168600 Adjacent sequences:  A306532 A306533 A306534 * A306536 A306537 A306538 KEYWORD nonn AUTHOR Alois P. Heinz, Feb 22 2019 STATUS approved

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Last modified January 18 13:49 EST 2020. Contains 331010 sequences. (Running on oeis4.)