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A036551
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a(n) = 2^(n-1)*(3^n-1) + 1.
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2
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1, 3, 17, 105, 641, 3873, 23297, 139905, 839681, 5038593, 30232577, 181397505, 1088389121, 6530342913, 39182073857, 235092475905, 1410554920961, 8463329656833, 50779978203137, 304679869743105, 1828079219507201, 10968475319140353, 65810851919036417
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = T(n, n), array T given by A048471.
a(n) = 9*a(n-1)-20*a(n-2)+12*a(n-3) for n>2.
G.f.: (1-6*x+10*x^2) / ((1-x)*(1-2*x)*(1-6*x)).
(End)
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PROG
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(PARI) Vec((1-6*x+10*x^2)/((1-x)*(1-2*x)*(1-6*x)) + O(x^30)) \\ Colin Barker, Aug 24 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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