A145777 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only either two adjacent vertically or two adjacent horizontally.

1, 1, 1, 2, 4, 7, 20, 66, 223, 972, 5286, 31417, 228724, 2000916, 20634823, 248726975, 3651917796, 62467383723, 1283523230287, 30987743547862, 900690199090722, 30606347558434592, 1253939853475088497, 60154380091248350142

Offset

1,4

Links

Table of n, a(n) for n=1..24.

Crossrefs

Sequence in context: A327444 A291403 A101805 * A188497 A237759 A306978

Adjacent sequences: A145774 A145775 A145776 * A145778 A145779 A145780

Keyword

nonn

Author

R. H. Hardin, Oct 18 2008

Status

approved