

A204295


Number of n X 2 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1, and 2 introduced before 3 in row major order.


1



0, 4, 4, 16, 68, 212, 776, 3076, 11540, 44944, 177748, 700292, 2779272, 11069140, 44107780, 176038288, 703199588, 2809956020, 11232774920, 44913243940, 179603461748, 718287355024, 2872823053300, 11490415637348, 45959392743048
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OFFSET

1,2


COMMENTS

Column 2 of A204301.


LINKS

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


FORMULA

Empirical: a(n) = 4*a(n1) +2*a(n2) +4*a(n3) 42*a(n4) 30*a(n5) +13*a(n6) +38*a(n7) +28*a(n8) 16*a(n9).


EXAMPLE

Some solutions for n=5:
..0..0....0..1....0..1....1..1....0..0....1..0....0..1....0..1....1..0....0..0
..1..1....0..1....0..1....0..0....1..1....1..0....0..1....0..1....1..0....1..1
..0..0....2..1....1..1....2..1....0..1....0..1....2..0....0..1....1..0....0..2
..1..1....1..0....0..0....1..1....0..0....0..1....1..0....1..0....1..0....0..1
..0..0....1..0....1..1....0..0....1..1....0..1....1..0....1..0....1..0....0..1


CROSSREFS

Cf. A204301.
Sequence in context: A203536 A038788 A010099 * A203101 A060691 A075225
Adjacent sequences: A204292 A204293 A204294 * A204296 A204297 A204298


KEYWORD

nonn


AUTHOR

R. H. Hardin, Jan 14 2012


STATUS

approved



