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A280435
Number of nX3 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.
1
1, 10, 21, 42, 77, 136, 236, 404, 687, 1162, 1959, 3294, 5528, 9262, 15497, 25898, 43233, 72100, 120132, 199992, 332675, 552970, 918491, 1524602, 2529072, 4192786, 6946941, 11503914, 19040117, 31497472, 52080284, 86073884, 142192983
OFFSET
1,2
COMMENTS
Column 3 of A280440.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) -a(n-2) -3*a(n-3) +a(n-4) +a(n-5) for n>6.
Empirical g.f.: x -x^2*(10-9*x-11*x^2+2*x^3) / ( (x-1)*(x^2+x-1)^2 ). - R. J. Mathar, Jan 04 2017
EXAMPLE
Some solutions for n=4
..0..0..1. .0..1..0. .0..0..1. .0..1..0. .0..1..0. .0..1..0. .0..1..0
..1..1..0. .1..1..1. .0..1..0. .1..0..1. .1..0..0. .0..1..0. .1..0..1
..0..0..1. .0..1..0. .1..0..1. .0..1..0. .0..1..0. .1..0..1. .1..1..0
..1..0..1. .1..0..1. .1..0..1. .0..1..1. .1..0..1. .0..0..1. .1..0..1
CROSSREFS
Cf. A280440.
Sequence in context: A256884 A089584 A192743 * A095824 A086225 A240994
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 03 2017
STATUS
approved