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A209376 1/4 the number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having distinct edge sums. 1
8, 17, 34, 80, 170, 410, 882, 2138, 4610, 11186, 24130, 58562, 126338, 306626, 661506, 1605506, 3463682, 8406530, 18136066, 44017154, 94961666, 230476802, 497225730, 1206792194, 2603507714, 6318845954, 13632143362, 33085906946, 71378829314 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A209382.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 4*a(n-4) + 4*a(n-5).

Empirical g.f.: x*(8 + 9*x - 31*x^2 - 8*x^3 + 20*x^4) / ((1 - x)*(1 - 6*x^2 + 4*x^4)). - Colin Barker, Jul 09 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A209382.

Sequence in context: A077221 A226601 A106648 * A159696 A049713 A297728

Adjacent sequences:  A209373 A209374 A209375 * A209377 A209378 A209379

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 07 2012

STATUS

approved

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Last modified July 19 09:33 EDT 2019. Contains 325155 sequences. (Running on oeis4.)