cp's OEIS Frontend

A260091 Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by seven: p(i)<>i and (i-p(i) mod n <= 7 or p(i)-i mod n <= 7).

%I A260091 #27 Jan 06 2016 12:08:35
%S A260091 1,0,1,2,9,44,265,1854,14833,133496,1334961,14684570,176214841,
%T A260091 2290792932,32071101049,481066515734,2649865335040,14570246018686,
%U A260091 80002336342276,438791546196382,2404416711392528,13164695578635648,72030936564665508,393911127182051942
%N A260091 Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by seven: p(i)<>i and (i-p(i) mod n <= 7 or p(i)-i mod n <= 7).
%C A260091 a(n) = A000166(n) for n <= 15.
%p A260091 a:= n-> `if`(n=0, 1, LinearAlgebra[Permanent](Matrix(n, (i, j)->
%p A260091         `if`(i<>j and (i-j mod n<=7 or j-i mod n<=7), 1, 0)))):
%p A260091 seq(a(n), n=0..16);
%t A260091 a[n_] := If[n == 0, 1, Permanent[Table[If[i != j && (Mod[i - j, n] <= 7 || Mod[j - i, n] <= 7), 1, 0], {i, 1, n}, {j, 1, n}]]]; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 0, 16}] (* _Jean-François Alcover_, Jan 06 2016, adapted from Maple *)
%Y A260091 Cf. A000166, A260074, A260081, A260092, A260094, A260111, A260115, A257953, A260216.
%Y A260091 Cf. A259780.
%K A260091 nonn
%O A260091 0,4
%A A260091 _Alois P. Heinz_, Jul 16 2015