

A280551


Number of nX5 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.


1



2, 87, 325, 832, 1764, 3438, 6386, 11506, 20389, 35757, 62317, 108150, 187115, 322925, 556071, 955574, 1638882, 2805542, 4794088, 8178068, 13927945, 23683803, 40214243, 68187902, 115469449, 195294823, 329919371, 556731676, 938492304
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OFFSET

1,1


COMMENTS

Column 5 of A280554.


LINKS

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


FORMULA

Empirical: a(n) = 6*a(n1) 12*a(n2) +5*a(n3) +12*a(n4) 12*a(n5) 3*a(n6) +6*a(n7) a(n9) for n>12


EXAMPLE

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


CROSSREFS

Cf. A280554.
Sequence in context: A306139 A317372 A177318 * A283945 A172736 A244386
Adjacent sequences: A280548 A280549 A280550 * A280552 A280553 A280554


KEYWORD

nonn


AUTHOR

R. H. Hardin, Jan 05 2017


STATUS

approved



