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A306524 Number of permutations p of [n] having at least one index i with |p(i)-i| = 2. 3
0, 0, 0, 3, 15, 86, 544, 3934, 32079, 292509, 2952702, 32712087, 394749367, 5155010088, 72440184064, 1090017765544, 17486996858151, 297965879586295, 5374189975316350, 102290550351854445, 2049025241258716927, 43089888746430771294, 949172134240270646352 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..450

Wikipedia, Permutation

FORMULA

a(n) = n! - A306523(n).

EXAMPLE

a(3) = 3: 231, 312, 321.

a(4) = 15: 1342, 1423, 1432, 2314, 2413, 2431, 3124, 3142, 3214, 3241, 3412, 3421, 4132, 4213, 4312.

CROSSREFS

Column k=2 of A306506.

Cf. A000142, A306523.

Sequence in context: A093615 A191148 A001931 * A180677 A220875 A075841

Adjacent sequences:  A306520 A306522 A306523 * A306525 A306527 A306528

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Feb 21 2019

STATUS

approved

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Last modified May 22 00:25 EDT 2019. Contains 323472 sequences. (Running on oeis4.)