A293045 - OEIS

A293045

Number of odd permutations s of {1,2,...,n} such that |s(i)-i| > 1 for each i=1,2,...,n.

0, 0, 0, 0, 0, 2, 15, 102, 854, 7852, 79867, 890348, 10799874, 141647368, 1997815108, 30156348228, 485117044074, 8285798537070, 149759338727585, 2855791585334774, 57300933786123530, 1206811729692494152, 26619251746350630597, 613691499376088985144

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OFFSET

0,6

LINKS

Table of n, a(n) for n=0..23.

Dmitry Efimov, Determinants of generalized binary band matrices, arXiv:1702.05655 [math.RA], 2017.

FORMULA

a(n) = (A001883(n) - d(n))/2, where d(n) = (3-n)/3 if n = 0 mod 3, d(n) = (n-1)/3 if n = 1 mod 3, d(n) = 0 if n = 2 mod 3.

CROSSREFS

Cf. A001883, A293044.

Sequence in context: A258390 A027080 A208347 * A372264 A081018 A006675

Adjacent sequences: A293042 A293043 A293044 * A293046 A293047 A293048

KEYWORD

nonn

AUTHOR

Eric M. Schmidt, Oct 09 2017

STATUS

approved