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A102486
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a(n) = 4*a(n - 1) - 5*a(n - 2).
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1
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2, 6, 14, 26, 34, 6, -146, -614, -1726, -3834, -6706, -7654, 2914, 49926, 185134, 490906, 1037954, 1697286, 1599374, -2088934, -16352606, -54965754, -138099986, -277571174, -419784766, -291283194, 933791054, 5191580186, 16097365474, 38431560966, 73239416494, 100799861146
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OFFSET
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0,1
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REFERENCES
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B. M. E. Moret and H. D. Shapiro, Algorithms from P to NP, Benjamin/Cummings, Vol. 1, 1991; p. 65.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (4,-5).
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FORMULA
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G.f.: 2*(1-x)/(1-4*x+5*x^2). [Colin Barker, Jan 14 2012]
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MAPLE
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a := proc(n) option remember; if n = 0 then RETURN(2) end if; if n = 1 then RETURN(6) end if; 4*a(n - 1) - 5*a(n - 2); end proc;
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MATHEMATICA
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Column[LinearRecurrence[{4, -5}, {2, 6}, 40]] (* Vincenzo Librandi, Jan 15 2012 *)
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PROG
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(MAGMA) I:=[2, 6]; [n le 2 select I[n] else 4*Self(n-1)-5*Self(n-2): n in [1..40]]; // Vincenzo Librandi, Jan 15 2012
(PARI) Vec(2*(1-x)/(1-4*x+5*x^2)+O(x^99)) \\ Charles R Greathouse IV, Jan 15 2012
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CROSSREFS
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Cf. A099456.
Sequence in context: A112853 A176752 A140759 * A063620 A162716 A138318
Adjacent sequences: A102483 A102484 A102485 * A102487 A102488 A102489
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KEYWORD
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sign,easy,changed
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AUTHOR
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N. J. A. Sloane, Feb 25 2005
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STATUS
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approved
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