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 A098659 Expansion of 1/sqrt((1-7*x)^2-24*x^2). 1
 1, 7, 61, 595, 6145, 65527, 712909, 7863667, 87615745, 983726695, 11112210781, 126142119187, 1437751935361, 16443380994775, 188609259215725, 2168833084841395, 24994269200292865, 288596644195946695, 3337978523215692925, 38666734085509918675 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES Rob Noble, Asymptotics of a family of binomial sums, J. Number Theory 130 (2010), no. 11, 2561-2585. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA G.f.: 1/sqrt(1-14*x+25*x^2). E.g.f.: exp(7*x)*BesselI(0, sqrt(24)*x) = exp(7*x)*BesselI(0, 2*sqrt(6)*x). a(n) = Sum_{k=0..n} C(n, k)^2*6^k. a(n) = [x^n] (1+7*x+6*x^2)^n. From Vaclav Kotesovec, Sep 15 2012: (Start) General recurrence for Sum_{k=0..n} C(n,k)^2*x^k (this is case x=6): (n+2)*a(n+2)-(x+1)*(2*n+3)*a(n+1)+(x-1)^2*(n+1)*a(n)=0. Asymptotic (Rob Noble, 2010): a(n) ~ (1+sqrt(x))^(2*n+1)/(2*x^(1/4)*sqrt(Pi*n)), this is case x=6. (End) MATHEMATICA Table[Sum[Binomial[n, k]^2*6^k, {k, 0, n}], {n, 0, 25}] (* Vaclav Kotesovec, Sep 15 2012 *) PROG (PARI) x='x+O('x^66); Vec(1/sqrt(1-14*x+25*x^2)) \\ Joerg Arndt, May 12 2013 CROSSREFS Cf. A000984, A001850, A069835, A084771, A084772. Sequence in context: A066443 A108448 A218473 * A269731 A199686 A113718 Adjacent sequences:  A098656 A098657 A098658 * A098660 A098661 A098662 KEYWORD easy,nonn AUTHOR Paul Barry, Sep 20 2004 STATUS approved

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