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Search: id:A080042
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| A080042 |
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a(n)=4a(n-1)+3a(n-2), a(0)=2, a(1)=4. |
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+0
3
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| 2, 4, 22, 100, 466, 2164, 10054, 46708, 216994, 1008100, 4683382, 21757828, 101081458, 469599316, 2181641638, 10135364500, 47086382914, 218751625156, 1016265649366, 4721317472932, 21934066839826, 101900219778100
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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G.f.: g(t)=(2-4t)/(1-4t-3t^2) a(n)=(2+sqrt(7))^n+(2-sqrt(7))^n
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MATHEMATICA
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CoefficientList[Series[(2 - 4t)/(1 - 4t - 3t^2), {t, 0, 25}], t]
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PROGRAM
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(Other) sage: [lucas_number2(n, 4, -3) for n in xrange(0, 22)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 14 2009]
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CROSSREFS
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Sequence in context: A071298 A152104 A047035 this_sequence A165588 A110130 A019025
Adjacent sequences: A080039 A080040 A080041 this_sequence A080043 A080044 A080045
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KEYWORD
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easy,nonn
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AUTHOR
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Mario Catalani (mario.catalani(AT)unito.it), Jan 21 2003
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