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A297300 Number of 3 X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 2 neighboring 1s. 1
1, 1, 3, 5, 9, 17, 32, 60, 113, 213, 401, 755, 1422, 2678, 5043, 9497, 17885, 33681, 63428, 119448, 224945, 423617, 797757, 1502339, 2829210, 5327978, 10033667, 18895437, 35583953, 67011825, 126196904, 237654452, 447551697, 842830925 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

FORMULA

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

Empirical g.f.: x*(1 - x)*(1 + x^2)^2 / (1 - 2*x + x^2 - 2*x^3 + x^4). - Colin Barker, Feb 26 2019

EXAMPLE

Some solutions for n=5:

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

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

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

CROSSREFS

Row 3 of A297299.

Sequence in context: A000213 A074858 A074860 * A213005 A171856 A205537

Adjacent sequences:  A297297 A297298 A297299 * A297301 A297302 A297303

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 27 2017

STATUS

approved

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Last modified November 20 10:09 EST 2019. Contains 329334 sequences. (Running on oeis4.)