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A204265 Permanent of n X n matrix M with M(i,j) = (i+j) (mod 3). 2
2, 2, 9, 40, 144, 1032, 7824, 48816, 530712, 5619456, 50015232, 707802624, 9591229440, 112586112000, 1938416832000, 32061464064000, 469224244224000, 9509523337728000, 185772505605120000, 3261008730405888000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Permanent of the n-th principal submatrix of A204263.

LINKS

Table of n, a(n) for n=1..20.

MATHEMATICA

f[i_, j_] := Mod[i + j, 3];

m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]

TableForm[m[8]] (* 8x8 principal submatrix *)

Flatten[Table[f[i, n + 1 - i],

  {n, 1, 14}, {i, 1, n}]]    (* A204263 *)

Permanent[m_] :=

  With[{a = Array[x, Length[m]]},

   Coefficient[Times @@ (m.a), Times @@ a]];

Table[Permanent[m[n]], {n, 1, 22}]    (* A204265 *)

PROG

(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

CROSSREFS

Cf. A204263.

Sequence in context: A180753 A220971 A205390 * A081086 A019514 A135816

Adjacent sequences:  A204262 A204263 A204264 * A204266 A204267 A204268

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jan 15 2012

STATUS

approved

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Last modified March 22 17:25 EDT 2019. Contains 321422 sequences. (Running on oeis4.)