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.
FORMULA
a(n) = A006067(2*n+1).
MATHEMATICA
a[n_] := A006067[[2n+1]];
a /@ Range[1, 13] (* Jean-François Alcover, Sep 14 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 19 2016
STATUS
approved