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Search: id:A098338
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| A098338 |
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Expansion of 1/sqrt(1-6x+13x^2). |
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+0
1
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| 1, 3, 7, 9, -21, -207, -911, -2769, -5213, 2457, 74997, 400491, 1409109, 3323583, 2219343, -27453951, -186624333, -750905127, -2088947819, -2955863589, 8506703569, 86421384387, 401183114163, 1280139325101, 2522745571021
(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 A098335. Second binomial transform of A098331. Central coefficients of (1+3x-x^2)^n.
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REFERENCES
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Tony D. Noe, On the Divisibility of Generalized Central Trinomial Coefficients, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.7.
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FORMULA
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E.g.f. : exp(3x)BesselI(0, 2*I*x), I=sqrt(-1); a(n)=sum{k=0..floor(n/2), binomial(n, k)binomial(n-k, k)3^n(-9)^(-k)}; a(n)=sum{k=0..floor(n/2), binomial(n, 2k)binomial(2k, k)3^n(-9)^(-k)}.
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CROSSREFS
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Sequence in context: A018267 A099886 A118564 this_sequence A033958 A018827 A057840
Adjacent sequences: A098335 A098336 A098337 this_sequence A098339 A098340 A098341
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 03 2004
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