

A242578


Number of length n+3 0..2 arrays with no four elements in a row with pattern aabb (with a!=b) and new values 0..2 introduced in 0..2 order.


1



13, 35, 97, 271, 757, 2115, 5913, 16535, 46237, 129291, 361537, 1010975, 2827013, 7905235, 22105577, 61814311, 172852717, 483351835, 1351607313, 3779529135, 10568780117, 29553711331, 82641690297, 231092768695, 646209770813
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OFFSET

1,1


LINKS

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


FORMULA

Empirical: a(n) = 4*a(n1)  5*a(n2) + 6*a(n3)  4*a(n4).
Empirical g.f.: x*(13  17*x + 22*x^2  20*x^3) / ((1  x)*(1  3*x + 2*x^2  4*x^3)).  Colin Barker, Nov 01 2018


EXAMPLE

Some solutions for n=4:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..0....1....0....0....0....1....0....1....1....1....1....0....1....1....0....1
..1....2....1....1....1....0....0....2....0....1....1....1....1....0....1....1
..2....1....0....0....0....2....1....1....1....2....0....2....2....0....2....2
..1....0....2....0....1....0....0....1....0....0....1....1....1....2....0....1
..2....2....1....0....0....2....0....1....2....2....2....1....2....1....2....0
..1....1....1....0....1....2....1....1....0....1....0....2....1....0....2....2


CROSSREFS

Column 2 of A242584.
Sequence in context: A227986 A228024 A243383 * A192145 A221592 A135172
Adjacent sequences: A242575 A242576 A242577 * A242579 A242580 A242581


KEYWORD

nonn


AUTHOR

R. H. Hardin, May 17 2014


STATUS

approved



