The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A188686 Binomial transform of the sequence of binomial(3n,n). 9
 1, 4, 22, 139, 934, 6484, 45931, 329893, 2393470, 17499892, 128732992, 951674398, 7064138779, 52616241370, 393052285291, 2943582912904, 22093111508686, 166141033332448, 1251528633163264, 9442096410241438, 71333250226656784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Binomial transform of A005809. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA G.f.: 2*cos((1/3)*arcsin(3/2*sqrt(3x/(1-x))))/sqrt(4-35x+31x^2). Recurrence: 2*n*(2*n-1)*a(n) = (39*n^2-43*n+12)*a(n-1) - 2*(n-1)*(33*n-34)*a(n-2) + 31*(n-2)*(n-1)*a(n-3). - Vaclav Kotesovec, Oct 20 2012 a(n) ~ 31^(n+1/2)/(6*4^n*sqrt(Pi*n)). - Vaclav Kotesovec, Oct 20 2012 MATHEMATICA Table[Sum[Binomial[n, k]Binomial[3k, k], {k, 0, n}], {n, 0, 22}] PROG (Maxima) makelist(sum(binomial(n, k)*binomial(3*k, k), k, 0, n), n, 0, 20); CROSSREFS Cf. A005809. Sequence in context: A142984 A283055 A097593 * A025756 A200731 A193116 Adjacent sequences:  A188683 A188684 A188685 * A188687 A188688 A188689 KEYWORD nonn,easy AUTHOR Emanuele Munarini, Apr 08 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 25 05:36 EDT 2022. Contains 354048 sequences. (Running on oeis4.)