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

%I #6 Oct 09 2017 23:21:42

%S 0,0,0,0,0,2,15,102,854,7852,79867,890348,10799874,141647368,

%T 1997815108,30156348228,485117044074,8285798537070,149759338727585,

%U 2855791585334774,57300933786123530,1206811729692494152,26619251746350630597,613691499376088985144

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

%H Dmitry Efimov, <a href="https://arxiv.org/abs/1702.05655">Determinants of generalized binary band matrices</a>, arXiv:1702.05655 [math.RA], 2017.

%F 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.

%Y Cf. A001883, A293044.

%K nonn

%O 0,6

%A _Eric M. Schmidt_, Oct 09 2017