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A204265 Permanent of n X n matrix M with M(i,j) = (i+j) (mod 3).

%I A204265 #10 Oct 19 2013 03:58:36
%S A204265 2,2,9,40,144,1032,7824,48816,530712,5619456,50015232,707802624,
%T A204265 9591229440,112586112000,1938416832000,32061464064000,469224244224000,
%U A204265 9509523337728000,185772505605120000,3261008730405888000
%N A204265 Permanent of n X n matrix M with M(i,j) = (i+j) (mod 3).
%C A204265 Permanent of the n-th principal submatrix of A204263.
%t A204265 f[i_, j_] := Mod[i + j, 3];
%t A204265 m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
%t A204265 TableForm[m[8]] (* 8x8 principal submatrix *)
%t A204265 Flatten[Table[f[i, n + 1 - i],
%t A204265   {n, 1, 14}, {i, 1, n}]]    (* A204263 *)
%t A204265 Permanent[m_] :=
%t A204265   With[{a = Array[x, Length[m]]},
%t A204265    Coefficient[Times @@ (m.a), Times @@ a]];
%t A204265 Table[Permanent[m[n]], {n, 1, 22}]    (* A204265 *)
%o A204265 (PARI) matperm(M)=my(n=#M,t);sum(i=1,n!,t=numtoperm(n,i);prod(j=1,n,M[j,t[j]]));a(n)=matperm(matrix(n,n,i,j,(i+j)%3)) \\ _Ralf Stephan_, Oct 19 2013
%Y A204265 Cf. A204263.
%K A204265 nonn
%O A204265 1,1
%A A204265 _Clark Kimberling_, Jan 15 2012