A145858 Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in two by two blocks.

1, 2, 1, 4, 6, 31, 37, 642, 380, 14860, 14318, 905572, 838039, 131446789, 91374201, 32141426467, 24653341080, 17110758261851, 12843811121650, 19746616596912795, 13295496951548212, 44660433163764744504

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Example

Maximal 7 X 7 example
.1.1.0.0.0.1.1
.1.1.0.0.0.1.1
.0.0.0.0.0.0.0
.0.0.0.0.0.0.0
.0.0.0.0.0.0.0
.0.1.1.0.1.1.0
.0.1.1.0.1.1.0

Crossrefs

Sequence in context: A019142 A330536 A268573 * A328491 A328357 A341696

Adjacent sequences: A145855 A145856 A145857 * A145859 A145860 A145861

Keyword

nonn

Author

R. H. Hardin, Oct 22 2008

Status

approved