A302636 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 6, 8, 14, 25, 47, 83, 150, 269, 488, 876, 1581, 2845, 5133, 9242, 16661, 30012, 54094, 97457, 175631, 316451, 570258, 1027529, 1851592, 3336392, 6012049, 10833241, 19520945, 35175378, 63384029, 114213840, 205806518, 370850169, 668249367

Offset

1,1

Comments

Row 3 of A302635.

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-2) +2*a(n-4) -a(n-5) for n>7

Example

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

Crossrefs

Cf. A302635.

Sequence in context: A246324 A280227 A181978 * A000937 A138001 A239659

Adjacent sequences: A302633 A302634 A302635 * A302637 A302638 A302639

Keyword

nonn

Author

R. H. Hardin, Apr 10 2018

Status

approved