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A080041
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a(n)=floor((1+sqrt(3))^n).
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0
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1, 2, 7, 20, 55, 152, 415, 1136, 3103, 8480, 23167, 63296, 172927, 472448, 1290751, 3526400, 9634303, 26321408, 71911423, 196465664, 536754175, 1466439680, 4006387711, 10945654784, 29904084991, 81699479552, 223207129087
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a(n)=A080040(n)-(1+(-1)^n)/2
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (2,3,-2,-2).
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FORMULA
| G.f.: g(t)=(1+2t^3)/( (t-1)*(1+t)*(2*t^2+2*t-1)).
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MATHEMATICA
| CoefficientList[Series[(1+2t^3)/(1-2t-3t^2+2t^3+2t^4), {t, 0, 30}], t]
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CROSSREFS
| Sequence in context: A035508 A018033 A000149 * A049681 A027120 A094982
Adjacent sequences: A080038 A080039 A080040 * A080042 A080043 A080044
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KEYWORD
| easy,nonn
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AUTHOR
| Mario Catalani (mario.catalani(AT)unito.it), Jan 21 2003
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