A260092 - OEIS

%I #18 Jan 06 2016 12:24:33

%S 1,0,1,2,9,44,265,1854,14833,133496,440192,1445100,4728000,15405008,

%T 49955280,162442816,530284304,1738077424,5714461760,18795784436,

%U 61868602624,203858323008,672535917712,2221505855492,7345985276816,24314075406208,80542683435168

%N Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by four: p(i)<>i and (i-p(i) mod n <= 4 or p(i)-i mod n <= 4).

%C a(n) = A000166(n) for n <= 9.

%p a:= n-> `if`(n=0, 1, LinearAlgebra[Permanent](Matrix(n, (i, j)->

%p         `if`(i<>j and (i-j mod n<=4 or j-i mod n<=4), 1, 0)))):

%p seq(a(n), n=0..15);

%t a[n_] := If[n == 0, 1, Permanent[Table[If[i != j && (Mod[i - j, n] <= 4 || Mod[j - i, n] <= 4), 1, 0], {i, 1, n}, {j, 1, n}]]]; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 0, 15}] (* _Jean-François Alcover_, Jan 06 2016, adapted from Maple *)

%Y Cf. A000166, A260074, A260081, A260094, A260111, A260091, A260115, A257953, A260216.

%Y Cf. A259777.

%K nonn

%O 0,4

%A _Alois P. Heinz_, Jul 15 2015