

A268255


Number of length(n+1) 0..2 arrays with new repeated values introduced in sequential order starting with zero.


1



7, 17, 42, 106, 273, 717, 1918, 5218, 14413, 40349, 114282, 326938, 943257, 2740797, 8010982, 23529346, 69385813, 205282157, 608959218, 1810358938, 5391414273, 16078923309, 48007516942, 143470822498, 429083952157, 1284051486077
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OFFSET

1,1


LINKS



FORMULA

Empirical: a(n) = 7*a(n1)  15*a(n2) + 7*a(n3) + 6*a(n4).
G.f.: x*(7  32*x + 28*x^2 + 18*x^3) / ((1  2*x)*(1  3*x)*(1  2*x  x^2)).
a(n) = 2^n + 3^n/2 + (3/41/sqrt(2))*(1sqrt(2))^n + (3/4+1/sqrt(2))*(1+sqrt(2))^n.
(End)


EXAMPLE

Some solutions for n=8:
..0....1....1....0....0....1....0....0....2....1....0....1....2....0....0....1
..0....0....0....0....0....0....0....2....0....2....1....2....1....1....0....0
..2....0....0....2....0....1....1....0....0....0....2....1....2....0....1....2
..0....1....0....0....2....0....0....0....0....0....1....2....1....0....0....0
..1....1....1....1....0....2....0....0....1....2....2....0....0....2....0....2
..0....1....2....1....2....0....1....1....1....1....1....0....1....1....1....1
..1....1....1....0....0....0....0....0....1....0....2....1....0....0....1....0
..0....1....2....1....2....2....2....0....2....1....0....0....0....1....1....0
..2....1....0....0....1....1....1....1....2....0....0....2....1....1....1....1


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



