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A163066
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a(n) = 12*a(n-1) - 31*a(n-2) for n > 1; a(0) = 2, a(1) = 17.
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2
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2, 17, 142, 1177, 9722, 80177, 660742, 5443417, 44838002, 369310097, 3041743102, 25052304217, 206333614442, 1699381942577, 13996241263222, 115274054938777, 949405180105442, 7819366458163217, 64400836914689902, 530409682773219097
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = ((2+sqrt(5))*(6+sqrt(5))^n + (2-sqrt(5))*(6-sqrt(5))^n)/2.
G.f.: (2-7*x)/(1-12*x+31*x^2).
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MATHEMATICA
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CoefficientList[Series[(2-7*x)/(1-12*x+31*x^2), {x, 0, 50}], x] (* or *) LinearRecurrence[{12, -31}, {2, 17}, 30] (* G. C. Greubel, Dec 22 2017 *)
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PROG
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(Magma) [ n le 2 select 15*n-13 else 12*Self(n-1)-31*Self(n-2): n in [1..20] ];
(PARI) x='x+O('x^30); Vec((2-7*x)/(1-12*x+31*x^2)) \\ G. C. Greubel, Dec 22 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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