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A204436 Permanent of the n-th principal submatrix of A204435. 3
1, 1, 1, 2, 6, 16, 80, 384, 1728, 12096, 82080, 525312, 4783104, 41886720, 349056000, 3891456000, 41803776000, 429981696000, 5667397632000, 72153317376000, 883878137856000, 13437405757440000, 197840194965504000, 2813727217287168000, 48450827875516416000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Also the number of permutations pi in S_n such that pi(i) + i != 0 (mod 3) for all i. - Peter Kagey, Jan 25 2021

LINKS

Table of n, a(n) for n=0..24.

MATHEMATICA

f[i_, j_] := Mod[(i + j)^2, 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}]]       (* A204435 *)

Join[{1}, Table[Permanent[m[n]], {n, 1, 22}]]   (* A204436 *)

CROSSREFS

Cf. A204235.

Sequence in context: A345246 A137858 A074740 * A135068 A147950 A147941

Adjacent sequences:  A204433 A204434 A204435 * A204437 A204438 A204439

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jan 15 2012

EXTENSIONS

a(0) and a(23)-a(24) from Pontus von Brömssen, Jan 29 2021

STATUS

approved

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Last modified October 26 08:00 EDT 2021. Contains 348267 sequences. (Running on oeis4.)