

A207094


Number of 0..2 arrays x(0..n1) of n elements with each no smaller than the sum of its two previous neighbors modulo 3.


1



3, 6, 12, 26, 55, 115, 239, 498, 1038, 2162, 4502, 9375, 19523, 40655, 84659, 176292, 367107, 764456, 1591886, 3314907, 6902887, 14374415, 29932954, 62331700, 129798109, 270288619, 562842849, 1172051097, 2440652442, 5082358916
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OFFSET

1,1


COMMENTS

Column 2 of A207100.


LINKS

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


FORMULA

Empirical: a(n) = 2*a(n1) + a(n4)  a(n6)  a(n9).
Empirical g.f.: x*(3 + 2*x^3  x^5  x^8) / ((1  x)*(1  x  x^2  x^3  2*x^4  2*x^5  x^6  x^7  x^8)).  Colin Barker, Jun 18 2018


EXAMPLE

Some solutions for n=5:
..1....0....1....0....0....0....0....0....1....0....1....1....0....0....0....0
..2....1....2....1....1....0....0....2....1....0....2....2....1....1....0....0
..2....1....1....1....2....0....2....2....2....0....1....2....2....2....0....0
..1....2....1....2....2....0....2....1....2....1....0....1....1....1....0....0
..2....2....2....0....1....1....2....2....2....2....1....0....2....0....0....2


CROSSREFS

Cf. A207100.
Sequence in context: A274476 A274059 A092886 * A135035 A054195 A054190
Adjacent sequences: A207091 A207092 A207093 * A207095 A207096 A207097


KEYWORD

nonn


AUTHOR

R. H. Hardin, Feb 15 2012


STATUS

approved



