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A280551 Number of n X 5 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1
2, 87, 325, 832, 1764, 3438, 6386, 11506, 20389, 35757, 62317, 108150, 187115, 322925, 556071, 955574, 1638882, 2805542, 4794088, 8178068, 13927945, 23683803, 40214243, 68187902, 115469449, 195294823, 329919371, 556731676, 938492304 (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) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 12*a(n-4) - 12*a(n-5) - 3*a(n-6) + 6*a(n-7) - a(n-9) for n>12.

Empirical g.f.: x*(2 + 75*x - 173*x^2 - 84*x^3 + 213*x^4 + 193*x^5 - 84*x^6 - 209*x^7 + 64*x^8 + 25*x^9 - 76*x^10 + 2*x^11) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 5 of A280554.

Sequence in context: A306139 A317372 A177318 * A283945 A172736 A244386

Adjacent sequences:  A280548 A280549 A280550 * A280552 A280553 A280554

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2017

STATUS

approved

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Last modified September 24 11:51 EDT 2021. Contains 347642 sequences. (Running on oeis4.)