A194569 Number of lower triangles of an n X n 0..1 array with new values introduced in row major order 0..1 and no element equal to more than two horizontal or vertical neighbors

1, 4, 25, 232, 3182, 65372, 1988549, 90079152, 6068358966, 607621801869, 90481144660781, 20030966609918016, 6592839659614699902, 3226130598077418710561, 2346968934938492776129480

Offset

1,2

Comments

Column 1 of A194576

Links

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

Example

Some solutions for 3X3
..0......0......0......0......0......0......0......0......0......0......0
..0.1....0.1....1.1....1.0....0.0....0.1....1.1....1.0....0.1....0.0....1.1
..1.1.0..0.1.0..1.0.1..1.1.0..1.0.1..0.1.1..1.0.0..1.0.1..0.0.0..1.1.1..0.1.0

Crossrefs

Sequence in context: A118835 A365053 A224080 * A356000 A198058 A099696

Adjacent sequences: A194566 A194567 A194568 * A194570 A194571 A194572

Keyword

nonn

Author

R. H. Hardin Aug 29 2011

Status

approved