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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
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

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Last modified December 9 00:32 EST 2019. Contains 329871 sequences. (Running on oeis4.)