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A144479
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a(0)=1, a(1)=3, a(n) = 8*a(n-1) - a(n-2).
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1
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1, 3, 23, 181, 1425, 11219, 88327, 695397, 5474849, 43103395, 339352311, 2671715093, 21034368433, 165603232371, 1303791490535, 10264728691909, 80814038044737, 636247575665987, 5009166567283159, 39437084962599285, 310487513133511121, 2444463020105489683
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = (((4-sqrt(15))^n*(1+sqrt(15))+(-1+sqrt(15))*(4+sqrt(15))^n))/(2*sqrt(15)). - Colin Barker, Oct 12 2015
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MATHEMATICA
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PROG
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(PARI) Vec((1-5*x)/(1-8*x+x^2) + O(x^40)) \\ Colin Barker, Oct 12 2015
(Magma) I:=[1, 3]; [n le 2 select I[n] else 8*Self(n-1)-Self(n-2): n in [1..30]]; // Vincenzo Librandi, Oct 12 2015
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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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