cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A214460 Number of 4 X 2*n+1 nonconsecutive chess tableaux.

Original entry on oeis.org

1, 1, 1, 1, 2, 9, 44, 233, 1472, 10610, 82828, 688511, 6042580, 55523953, 530498426, 5242548633, 53361716373, 557495995958, 5961086843092, 65077096683358, 723862991146939, 8189257485453446, 94087399914391254, 1096331953010025684, 12941148147430923798
Offset: 0

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Author

Alois P. Heinz, Jul 18 2012

Keywords

Comments

A standard Young tableau (SYT) with cell(i,j)+i+j == 1 mod 2 for all cells where entries m and m+1 never appear in the same row is called a nonconsecutive chess tableau.

Examples

			a(4) = 2:
  [1, 4,  7, 12, 15, 20, 23, 28, 31]  [1,   4,  7, 10, 13, 16, 19, 22, 25]
  [2, 5, 10, 13, 18, 21, 26, 29, 34]  [2,   5,  8, 11, 14, 17, 28, 31, 34]
  [3, 8, 11, 16, 19, 24, 27, 32, 35]  [3,   6,  9, 20, 23, 26, 29, 32, 35]
  [6, 9, 14, 17, 22, 25, 30, 33, 36]  [12, 15, 18, 21, 24, 27, 30, 33, 36].
		

Crossrefs

Bisection (odd part) of row n=4 of A214088.

Programs

  • Maple
    b:= proc(l, t) option remember; local n, s;
           n, s:= nops(l), add(i, i=l);
          `if`(s=0, 1, add(`if`(t<>i and irem(s+i-l[i], 2)=1 and l[i]>
          `if`(i=n, 0, l[i+1]), b(subsop(i=l[i]-1, l), i), 0), i=1..n))
        end:
    a:= n-> b([(2*n+1)$4], 0):
    seq(a(n), n=0..25);
  • Mathematica
    b[l_List, t_] := b[l, t] = Module[{n, s}, {n, s} = {Length[l], Total[l]}; If[s == 0, 1, Sum[If[t != i && Mod[s + i - l[[i]], 2] == 1 && l[[i]] > If[i == n, 0, l[[i+1]]], b[ReplacePart[l, i -> l[[i]]-1], i], 0], {i, 1, n}]]]; a[n_] := b[{2n+1, 2n+1, 2n+1, 2n+1}, 0]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Jul 15 2017, translated from Maple *)

Formula

a(n) ~ c * 16^n / n^(15/2), where c = 5.347555... - Vaclav Kotesovec, Dec 05 2017