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Search: id:A084772
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| A084772 |
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Coefficients of 1/sqrt(1-12*x+16*x^2); also, a(n) is the central coefficient of (1+6x+5x^2)^n. |
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+0
1
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| 1, 6, 46, 396, 3606, 33876, 324556, 3151896, 30915046, 305543556, 3038019876, 30354866856, 304523343996, 3065412858696, 30946859111256, 313206733667376, 3176825392214406, 32284147284682596, 328643023505612596
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=sum(k=0, n, 5^k*C(n, k)^2) - Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 26 2003
E.g.f. : exp(6*x)*BesselI(0, 2sqrt(5)*x) - Paul Barry (pbarry(AT)wit.ie), Sep 20 2004
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EXAMPLE
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G.f.: 1/sqrt(1-2*b*x+(b^2-4*c)*x^2) yields central coefficients of (1+b*x+c*x^2)^n.
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PROGRAM
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(PARI) for(n=0, 30, t=polcoeff((1+6*x+5*x^2)^n, n, x); print1(t", "))
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CROSSREFS
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Adjacent sequences: A084769 A084770 A084771 this_sequence A084773 A084774 A084775
Sequence in context: A079910 A103768 A073507 this_sequence A111531 A052781 A049378
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jun 10 2003
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