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A306675 Number of permutations p of [2n] having at least one index i with |p(i)-i| = n. 3
0, 1, 15, 455, 25487, 2293839, 302786759, 55107190151, 13225725636255, 4047072044694047, 1537887376983737879, 710503968166486900119, 392198190427900768865711, 254928823778135499762712175, 192726190776270437820610404327, 167671785975355280903931051764519 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..224

Wikipedia, Permutation

FORMULA

a(n) = A306506(2n,n).

a(n) = (2n)! - A306535(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-> (2*n)! -b(0, 2*n):

seq(a(n), n=0..16);

CROSSREFS

Cf. A306506, A306535.

Sequence in context: A041423 A041420 A036506 * A219561 A209488 A320097

Adjacent sequences:  A306672 A306673 A306674 * A306676 A306677 A306678

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Mar 04 2019

STATUS

approved

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Last modified January 25 19:09 EST 2020. Contains 331249 sequences. (Running on oeis4.)