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Search: id:A098456
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| A098456 |
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Expansion of 1/sqrt(1-4x-64x^2). |
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+0
1
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| 1, 2, 38, 212, 2566, 20092, 210524, 1884136, 18854854, 178415852, 1764019828, 17115907096, 169100140444, 1661540282456, 16458178007288, 162887627833552, 1618680238292294, 16095872154638156, 160435286115927044
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Define Q(n,x)=sum{k=0..floor(n/2), binomial(n,k)binomial(2(n-k),n)x^(n-2k)}. Then a(n)=4^n*Q(n,1/4). Central coefficients of (1+2x+17x^2)^n.
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FORMULA
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E.g.f.: exp(2x)BesselI(0, 2sqrt(17)x); a(n)=sum{k=0..floor(n/2), binomial(n, k)binomial(2(n-k), n)16^k}.
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CROSSREFS
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Cf. A084770, A098455.
Sequence in context: A050248 A075459 A105645 this_sequence A126731 A046845 A098772
Adjacent sequences: A098453 A098454 A098455 this_sequence A098457 A098458 A098459
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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 08 2004
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