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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 January 30 21:42 EST 2023. Contains 359947 sequences. (Running on oeis4.)