A156476 Number of n X n arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 21.

54, 20, 3552, 11364, 2742240, 56271108, 23882769984, 990946452040, 760348893638560

Offset

4,1

Links

Table of n, a(n) for n=4..12.

Crossrefs

Sequence in context: A096510 A236178 A247389 * A137939 A033374 A247897

Adjacent sequences: A156473 A156474 A156475 * A156477 A156478 A156479

Keyword

nonn

Author

R. H. Hardin Feb 09 2009

Status

approved