A156430 Number of n X n arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 2.

1, 2, 10, 12, 84, 132, 954, 1728, 13290, 26820, 217500, 481320, 4086600, 9783480, 86549820, 221921280, 2037627900, 5552479800, 52745205240, 151802154000, 1487961422640, 4500041903280, 45412066438200, 143712079822080

Offset

2,2

Links

Table of n, a(n) for n=2..25.

Crossrefs

Sequence in context: A181427 A055697 A055705 * A347336 A303356 A299317

Adjacent sequences: A156427 A156428 A156429 * A156431 A156432 A156433

Keyword

nonn

Author

R. H. Hardin Feb 09 2009

Status

approved