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A280553 Number of n X 7 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
13, 400, 1316, 3182, 6386, 11697, 20334, 34360, 57389, 95548, 159360, 266756, 448302, 755986, 1278112, 2164458, 3668734, 6220179, 10544150, 17865068, 30247639, 51170104, 86486508, 146040766, 246372038, 415246118, 699240242 (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*(13 + 322*x - 928*x^2 + 21*x^3 + 930*x^4 + 341*x^5 - 79*x^6 - 480*x^7 - 148*x^8 - 205*x^9 - 238*x^10 + 6*x^11) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 7 of A280554.

Sequence in context: A009010 A171196 A286189 * A162446 A284824 A075672

Adjacent sequences:  A280550 A280551 A280552 * A280554 A280555 A280556

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2017

STATUS

approved

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Last modified October 18 05:18 EDT 2019. Contains 328146 sequences. (Running on oeis4.)