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%I #19 Aug 19 2021 02:33:20
%S 1,3,19,86,1060,13276,215308,3086544,68937280,1552257216,40750688448,
%T 987692033664,31883024335104,1036810188322560,37597332892066560,
%U 1285416947916933120,54309158991453634560,2309262618253981040640,106842526312699253145600
%N Permanent of the n-th principal submatrix of A204255.
%H Vaclav Kotesovec, <a href="/A204256/b204256.txt">Table of n, a(n) for n = 0..35</a>
%t f[i_, j_] := 1 + Mod[i + j, 4];
%t m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
%t TableForm[m[8]] (* 8x8 principal submatrix *)
%t Flatten[Table[f[i, n + 1 - i],
%t {n, 1, 12}, {i, 1, n}]] (* A204255 *)
%t Join[{1},Table[Permanent[m[n]], {n, 1, 20}]] (* A204256 *)
%o (PARI) a(n) = matpermanent(matrix(n, n, i, j, 1 + ((i+j) % 4))); \\ _Michel Marcus_, Jan 30 2021
%Y Cf. A204255.
%K nonn
%O 0,2
%A _Clark Kimberling_, Jan 14 2012
%E a(0) and a(18) from _Pontus von Brömssen_, Jan 30 2021
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