A141483 Number of n X n binary matrices, symmetric under horizontal and vertical reflection, with no more than 1 one in any 2 X 2 subblock.

1, 2, 1, 5, 2, 35, 5, 314, 35, 6427, 314, 202841, 6427, 12727570, 202841, 1355115601, 12727570, 269718819131, 1355115601, 94707789944544, 269718819131, 60711713670028729, 94707789944544, 69645620389200894313

Offset: 0

Author

R. H. Hardin, Aug 09 2008

Keywords

• nonn

Comments

a(2n-1) = A063443(n+1). - Vaclav Kotesovec, May 01 2012

a(2n) = a(2n-3), for n>1. - Vaclav Kotesovec, Apr 01 2016

Links

• R. H. Hardin and Vaclav Kotesovec, Table of n, a(n) for n = 0..78 (terms 0..30 from R. H. Hardin, terms 31..78 after A063443)