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A297220 Number of n X 4 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 neighboring 1s. 1
4, 16, 57, 207, 751, 2720, 9861, 35741, 129540, 469528, 1701805, 6168220, 22356839, 81032722, 293704534, 1064537220, 3858433620, 13984959985, 50688731051, 183722188635, 665904273716, 2413581640617, 8748068704189, 31707527421628 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 6*a(n-2) + 11*a(n-3) + 6*a(n-4) + a(n-5).

Empirical g.f.: x*(2 + x)^2*(1 + 2*x + 2*x^2) / (1 - x - 6*x^2 - 11*x^3 - 6*x^4 - x^5). - Colin Barker, Feb 26 2019

EXAMPLE

Some solutions for n=7:

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

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

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

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

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

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

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

CROSSREFS

Column 4 of A297224.

Sequence in context: A281064 A122032 A197674 * A297375 A283124 A282393

Adjacent sequences:  A297217 A297218 A297219 * A297221 A297222 A297223

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 27 2017

STATUS

approved

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Last modified October 15 17:24 EDT 2019. Contains 328037 sequences. (Running on oeis4.)