A192840 Number of n X n symmetric 0..1 arrays with each element equal to at least two horizontal or vertical neighbors, containing at least one 1 and with new values 0..1 introduced in lower triangular row major order

0, 0, 0, 4, 23, 183, 2051, 34480, 852316, 31436447, 1719054682, 139749375351, 16887682211104, 3032513808121100, 809442991768500675, 321179427812462958356, 189437827654558885755437

Offset

1,4

Links

R. H. Hardin, Table of n, a(n) for n = 1..19

Example

Some solutions for 6X6
..0..0..0..0..1..1....0..0..0..0..1..1....0..0..0..0..0..0....0..0..0..0..1..1
..0..0..0..0..1..1....0..0..0..0..1..1....0..0..0..0..0..0....0..1..1..0..1..1
..0..0..0..0..0..0....0..0..0..0..1..1....0..0..1..1..1..1....0..1..1..0..0..0
..0..0..0..1..1..0....0..0..0..1..1..1....0..0..1..1..1..1....0..0..0..1..1..0
..1..1..0..1..1..0....1..1..1..1..0..0....0..0..1..1..0..0....1..1..0..1..1..0
..1..1..0..0..0..0....1..1..1..1..0..0....0..0..1..1..0..0....1..1..0..0..0..0

Crossrefs

Sequence in context: A106174 A056814 A058863 * A302189 A292971 A317967

Adjacent sequences: A192837 A192838 A192839 * A192841 A192842 A192843

Keyword

nonn

Author

R. H. Hardin Jul 11 2011

Status

approved