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Search: id:A100139
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| A100139 |
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Sum C(n-3k,3k)3^k*2^(n-6k), k=0..floor(n/6). |
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+0
2
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| 1, 2, 4, 8, 16, 32, 67, 152, 376, 992, 2704, 7424, 20233, 54398, 144112, 376736, 974368, 2500544, 6385435, 16264220, 41396788, 105423776, 268818064, 686499008, 1755723793, 4495691834, 11521647916, 29543647160, 75774096832, 194353495424
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Binomial transform of 1,1,1,1,1,1,4,4,13,13,31,... with g.f. (1-x)^2(1+x)^3/(1-3x^2+3x^4-4x^6)=(1+x)(1-x^2)^2/((1-x^2)^3-3x^6).
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FORMULA
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G.f.: (1-2x)^2/((1-2x)^3-3x^6); a(n)=6a(n-1)-12a(n-2)+8a(n-3)+3a(n-6).
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CROSSREFS
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Cf. A097122, A100134.
Adjacent sequences: A100136 A100137 A100138 this_sequence A100140 A100141 A100142
Sequence in context: A141366 A049142 A100138 this_sequence A076766 A035523 A078227
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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), Nov 06 2004
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