

A281831


Number of nX2 0..1 arrays with no element equal to more than four of its kingmove neighbors and with new values introduced in order 0 sequentially upwards.


7



2, 8, 31, 121, 472, 1841, 7181, 28010, 109255, 426157, 1662256, 6483749, 25290329, 98646746, 384778723, 1500857065, 5854200856, 22834731209, 89068510325, 347418126314, 1355129372335, 5285779516597, 20617562919424, 80420286052733
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OFFSET

1,1


COMMENTS



LINKS



FORMULA

Empirical: a(n) = 3*a(n1) +3*a(n2) +2*a(n3)


EXAMPLE

Some solutions for n=4
..0..0. .0..0. .0..1. .0..0. .0..0. .0..0. .0..0. .0..1. .0..0. .0..1
..0..1. .0..0. .1..0. .1..0. .1..0. .1..1. .1..1. .1..0. .1..0. .0..1
..0..0. .0..1. .1..1. .0..1. .1..1. .0..1. .0..1. .1..0. .0..1. .1..1
..0..0. .0..0. .1..0. .0..0. .0..0. .0..0. .0..1. .1..1. .0..1. .1..1


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



