A156432 Number of n X n arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 3.

1, 6, 12, 136, 294, 3924, 9712, 156128, 424980, 8019000, 23622288, 509911008, 1609793976, 39027027088, 131023800192, 3518648357632, 12483723152016, 367381371180384, 1370345745388480, 43811251070582400, 171071079764322144

Offset

3,2

Links

Table of n, a(n) for n=3..23.

Crossrefs

Sequence in context: A102077 A102062 A164584 * A070020 A308565 A341106

Adjacent sequences: A156429 A156430 A156431 * A156433 A156434 A156435

Keyword

nonn

Author

R. H. Hardin Feb 09 2009

Status

approved