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A251203 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock summing to a nonzero multiple of 2. 1
40, 180, 816, 3728, 17152, 79424, 369920, 1731840, 8144896, 38458368, 182218752, 865931264, 4125491200, 19697254400, 94217240576, 451363012608, 2165141143552, 10397297147904, 49974875258880, 240389177999360, 1157058166521856 (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) = 8*a(n-1) - 12*a(n-2) - 16*a(n-3).

Empirical g.f.: 4*x*(10 - 35*x - 36*x^2) / ((1 - 4*x)*(1 - 4*x - 4*x^2)). - Colin Barker, Nov 26 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Column 1 of A251210.

Sequence in context: A264547 A251210 A211497 * A187510 A187379 A077818

Adjacent sequences:  A251200 A251201 A251202 * A251204 A251205 A251206

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 30 2014

STATUS

approved

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Last modified June 19 17:16 EDT 2019. Contains 324222 sequences. (Running on oeis4.)