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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.)