A272070 Number of ways to quarter a 2n+1 X 2n+1 chessboard with central square removed.

1, 7, 104, 3970, 431932, 137066448, 128095791922, 355704307903818, 2952926822418475378, 73569487283165427567144, 5515501712040561162370942752, 1246743475892797935712690352483842, 850999652841310762943520023896881419780

Offset

1,2

Comments

The chessboard must be dissected into four identical pieces. All solutions have 90-degree rotational symmetry and solutions that differ only by rotation or reflection are considered equivalent.

Links

Table of n, a(n) for n=1..13.

Formula

a(n) = A006067(2*n+1).

Mathematica

A006067 = Import["https://oeis.org/A006067/b006067.txt", "Table"][[All, 2]];
a[n_] := A006067[[2n+1]];
a /@ Range[1, 13] (* Jean-François Alcover, Sep 14 2019 *)

Crossrefs

Cf. A006067, A064941, A257952.

Sequence in context: A001921 A215552 A357344 * A098362 A093741 A139742

Adjacent sequences: A272067 A272068 A272069 * A272071 A272072 A272073

Keyword

nonn

Author

Andrew Howroyd, Apr 19 2016

Status

approved