A232937 - OEIS

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A232937

Number of n X 4 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, vertically or antidiagonally.

24, 56, 252, 1048, 4458, 18850, 79810, 337850, 1430144, 6054098, 25627862, 108487018, 459242866, 1944049234, 8229473620, 34836688334, 147469316688, 624261386538, 2642599067830, 11186547787492, 47354459831826

(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) + 10*a(n-2) + 15*a(n-3) + 4*a(n-4) - 6*a(n-5) - a(n-6) + 3*a(n-7) - a(n-8) for n>9.

Empirical g.f.: 2*x*(12 + 16*x - 22*x^2 - 62*x^3 - 23*x^4 + 26*x^5 + 6*x^6 - 13*x^7 + 4*x^8) / (1 - x - 10*x^2 - 15*x^3 - 4*x^4 + 6*x^5 + x^6 - 3*x^7 + x^8). - Colin Barker, Oct 06 2018

EXAMPLE

Some solutions for n=5:

..0..1..0..0....2..2..2..2....2..1..2..1....2..2..2..2....1..0..0..0

..0..0..0..0....2..2..2..2....2..2..2..2....1..2..2..2....0..0..0..0

..1..0..1..0....1..2..2..2....2..2..2..1....2..2..2..1....0..0..1..0

..0..0..0..0....2..2..2..2....2..2..2..2....2..1..2..2....0..0..0..0

..1..0..0..1....2..2..2..2....1..2..1..2....2..2..1..2....0..1..0..0

CROSSREFS

Column 4 of A232941.

Sequence in context: A043978 A211461 A208086 * A190104 A255968 A211325

Adjacent sequences: A232934 A232935 A232936 * A232938 A232939 A232940

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 02 2013

STATUS

approved