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A189748
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a(n) = 5*a(n-1) + 4*a(n-2) with a(1)=5, a(2)=4.
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12
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5, 4, 40, 216, 1240, 7064, 40280, 229656, 1309400, 7465624, 42565720, 242691096, 1383718360, 7889356184, 44981654360, 256465696536, 1462255100120, 8337138286744, 47534711834200, 271022112317976, 1545249408926680, 8810335493905304, 50232675105233240
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OFFSET
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1,1
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..100
Index entries for linear recurrences with constant coefficients, signature (5, 4).
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FORMULA
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a(n) = 5/2*((5/2-1/2*sqrt(41))^(n-1)+(5/2+1/2*sqrt(41))^(n-1))+17/82*sqrt(41)*((5/2 -1/2*sqrt(41))^(n-1)-(5/2+1/2*sqrt(41))^(n-1)). - Paolo P. Lava, May 24 2011
G.f.: x*(5-21*x)/(1-5*x-4*x^2). - Bruno Berselli, May 24 2011
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MATHEMATICA
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LinearRecurrence[{5, 4}, {5, 4}, 40]
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PROG
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(Maxima) a[1]:5$ a[2]:4$ a[n]:=5*a[n-1]+4*a[n-2]$ makelist(a[n], n, 1, 23); [Bruno Berselli, May 24 2011]
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CROSSREFS
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Cf. A000045, A000079, A105476, A159612, A080040, A135522, A103435, A189732, A189734, A189735, A189736, A189737, A189738, A189739, A189741, A189742, A189743, A189744, A189745, A189746, A189747, A189749.
Sequence in context: A078811 A093399 A123233 * A304151 A223527 A262421
Adjacent sequences: A189745 A189746 A189747 * A189749 A189750 A189751
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KEYWORD
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nonn
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AUTHOR
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Harvey P. Dale, Apr 26 2011
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STATUS
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approved
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