A156433 Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 3.

1, 2, 0, 0, 42, 276, 0, 0, 20340, 216680, 0, 0, 30693320, 449345680, 0, 0, 105796267920, 1972495637280, 0, 0, 696951215563680, 15784392403940160, 0, 0, 7817495632183997760, 208339434598512497280, 0, 0

Offset

3,2

Links

Table of n, a(n) for n=3..30.

Crossrefs

Sequence in context: A013369 A013416 A365973 * A169771 A365982 A326779

Adjacent sequences: A156430 A156431 A156432 * A156434 A156435 A156436

Keyword

nonn

Author

R. H. Hardin Feb 09 2009

Status

approved