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Search: id:A098590
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| 1, 4, 16, 64, 257, 1032, 4144, 16640, 66817, 268300, 1077344, 4326016, 17370881, 69751824, 280084640, 1124664576, 4516029185, 18133868564, 72815558896, 292386900160, 1174063629825, 4714388387864, 18930369110352, 76013863341568
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OFFSET
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0,2
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FORMULA
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G.f.: 1/(1-4x-x^4); a(n)=sum{k=0..floor(n/3), binomial(n-3k, k)4^(n-4k)}.
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MAPLE
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K:=1/(1+4*z-z^4): Kser:=series(K, z=0, 30): seq(abs(coeff(Kser, z, n)), n= 0..23); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 08 2007
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MATHEMATICA
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CoefficientList[Series[x/(1 - 4*x - x^4), {x, 0, 25}], x] - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 29 2007
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CROSSREFS
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Cf. A052541.
Sequence in context: A083592 A069029 A083589 this_sequence A071357 A142872 A113995
Adjacent sequences: A098587 A098588 A098589 this_sequence A098591 A098592 A098593
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 16 2004
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