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A280550 Number of n X 4 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
1, 34, 144, 382, 832, 1666, 3182, 5886, 10680, 19122, 33920, 59754, 104690, 182598, 317264, 549398, 948528, 1633186, 2805094, 4807006, 8220440, 14030634, 23904656, 40659818, 69051850, 117099910, 198312144, 335420782, 566645728, 956190466 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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>11.

Empirical g.f.: x*(1 + 28*x - 48*x^2 - 79*x^3 + 86*x^4 + 142*x^5 - 57*x^6 - 134*x^7 + 46*x^8 + 39*x^9 - 36*x^10) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 4 of A280554.

Sequence in context: A158062 A141127 A153465 * A105714 A072319 A031398

Adjacent sequences:  A280547 A280548 A280549 * A280551 A280552 A280553

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2017

STATUS

approved

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Last modified September 17 19:58 EDT 2021. Contains 347489 sequences. (Running on oeis4.)