A301842 - OEIS

A301842

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

2, 8, 25, 81, 263, 855, 2778, 9027, 29333, 95316, 309725, 1006437, 3270370, 10626915, 34531665, 112209036, 364618033, 1184809305, 3849982618, 12510339087, 40651763813, 132096011916, 429239834325, 1394794836717, 4532320816850

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Row 2 of A301841.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) +a(n-2) -2*a(n-4) for n>6

EXAMPLE

Some solutions for n=5

..0..1..1..0..0. .0..0..1..0..0. .0..0..0..1..1. .0..1..0..1..1

..0..0..1..0..0. .0..0..0..1..1. .1..0..1..0..0. .1..1..0..0..0

CROSSREFS

Cf. A301841.

Sequence in context: A037560 A138804 A212323 * A240478 A288539 A281338

Adjacent sequences: A301839 A301840 A301841 * A301843 A301844 A301845

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 27 2018

STATUS

approved