A303422 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2, 3, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 32, 252, 1985, 15647, 123337, 972168, 7662841, 60400282, 476088932, 3752642337, 29579189147, 233149966025, 1837741608616, 14485501658565, 114178052735590, 899977648952776, 7093830637396745, 55915203194889879, 440736480491065049

Offset

1,1

Comments

Row 3 of A303421.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 7*a(n-1) +4*a(n-2) +21*a(n-3) +18*a(n-4)

Example

Some solutions for n=5
..0..1..1..1..1. .0..0..0..0..1. .0..0..0..0..0. .0..0..1..0..1
..1..1..0..1..0. .1..1..0..0..0. .0..1..0..1..1. .0..1..0..0..0
..1..0..0..1..0. .1..1..0..1..0. .1..0..0..1..0. .1..0..0..0..0

Crossrefs

Cf. A303421.

Sequence in context: A317520 A300203 A273053 * A301402 A303416 A007278

Adjacent sequences: A303419 A303420 A303421 * A303423 A303424 A303425

Keyword

nonn

Author

R. H. Hardin, Apr 23 2018

Status

approved