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Search: id:A099583
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| A099583 |
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Sum C(n-k,k-1)2^(n-k-1)(3/2)^(k-1), k=0..floor(n/2). |
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+0
1
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| 0, 0, 1, 2, 10, 26, 91, 260, 820, 2420, 7381, 22022, 66430, 198926, 597871, 1792520, 5380840, 16139240, 48427561, 145272842, 435848050, 1307514626, 3922632451, 11767808780, 35303692060, 105910810460, 317733228541, 953198888462
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OFFSET
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0,4
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COMMENT
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In general a(n)=sum{k=0..floor(n/2), C(n-k,k-1)u^(n-k-1)(v/u)^(k-1)} has g.f. x^2/((1-v*x^2)(1-u*x-v*x^2)) and satisfies the recurrence a(n)=u*a(n-1)+2v*a(n-2)-u*v*a(n-3)-v^2*a(n-4).
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FORMULA
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G.f.: x^2/((1-3x^2)(1-2x-3x^2)); a(n)=2a(n-1)+6a(n-2)-6a(n-3)-9a(n-4).
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CROSSREFS
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Sequence in context: A099969 A025589 A084182 this_sequence A133479 A057753 A060515
Adjacent sequences: A099580 A099581 A099582 this_sequence A099584 A099585 A099586
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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), Oct 23 2004
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