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A296380
Number of n X 2 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 1 or 2 neighboring 1s.
2
2, 10, 28, 86, 279, 869, 2728, 8596, 27004, 84888, 266917, 839085, 2637906, 8293166, 26071968, 81965142, 257682603, 810103353, 2546806304, 8006660936, 25171373608, 79133870240, 248781395465, 782119995913, 2458832133618, 7730086808818
OFFSET
1,1
COMMENTS
Column 2 of A296386.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + 6*a(n-3) - 6*a(n-4) + 6*a(n-5) - 5*a(n-6) + 3*a(n-7) - a(n-8).
Empirical g.f.: x*(1 + x - x^2)*(2 + 2*x + 2*x^3 - x^4 + x^5) / (1 - 3*x + x^2 - 6*x^3 + 6*x^4 - 6*x^5 + 5*x^6 - 3*x^7 + x^8). - Colin Barker, Mar 22 2018
EXAMPLE
Some solutions for n=5:
..1..0. .0..1. .0..0. .0..0. .0..1. .0..0. .1..0. .1..1. .1..1. .0..1
..1..0. .1..0. .0..0. .0..1. .0..1. .0..0. .1..0. .0..1. .0..0. .1..1
..1..0. .1..0. .1..0. .1..0. .0..0. .0..0. .0..1. .1..0. .1..0. .0..0
..0..0. .1..0. .1..1. .0..1. .0..1. .1..0. .0..1. .0..1. .1..1. .1..1
..1..1. .0..0. .0..1. .0..1. .1..1. .1..0. .0..1. .1..1. .0..1. .0..1
CROSSREFS
Cf. A296386.
Sequence in context: A006331 A252591 A296849 * A291053 A104657 A000900
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 11 2017
STATUS
approved