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 A280436 Number of nX4 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
 2, 20, 42, 80, 138, 232, 386, 640, 1062, 1764, 2934, 4884, 8134, 13548, 22562, 37560, 62498, 103936, 172746, 286936, 476318, 790220, 1310222, 2171180, 3595918, 5952452, 9848346, 16286240, 26920122, 44477464, 73454354, 121259824, 200099094 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 4 of A280440. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 4*a(n-1) -4*a(n-2) -2*a(n-3) +4*a(n-4) -a(n-6) for n>7. Empirical g.f.: 2*x + 2*x^2*(10-19*x-4*x^2+13*x^3+x^5+2*x^4) / ( (x-1)^2*(x^2+x-1)^2 ). - R. J. Mathar, Jan 04 2017 EXAMPLE Some solutions for n=4 ..0..1..1..0. .0..1..0..1. .0..1..1..0. .0..0..1..0. .0..1..0..1 ..1..0..0..1. .1..0..0..0. .1..0..0..1. .1..0..1..0. .1..0..1..0 ..0..1..1..0. .0..1..0..1. .0..1..1..0. .0..1..0..1. .0..1..0..1 ..1..0..1..0. .1..0..1..0. .0..1..0..1. .1..0..1..0. .1..0..0..1 CROSSREFS Cf. A280440. Sequence in context: A269669 A293930 A194999 * A266842 A254542 A202602 Adjacent sequences:  A280433 A280434 A280435 * A280437 A280438 A280439 KEYWORD nonn AUTHOR R. H. Hardin, Jan 03 2017 STATUS approved

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Last modified December 12 09:36 EST 2019. Contains 329953 sequences. (Running on oeis4.)