This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A278689 a(n) = Sum_{k=0..n} binomial(n+k,n)*binomial(2*n-3,n-k-1) for n>1, a(n) = n for n<=1. 1
 0, 1, 4, 25, 170, 1204, 8736, 64416, 480480, 3615040, 27382784, 208539136, 1595216896, 12247746560, 94330470400, 728474664960, 5638832087040, 43737154928640, 339856038297600, 2645063771750400, 20615846154731520, 160889637246074880, 1257082279931412480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 FORMULA G.f.: (sqrt(1-8*x)*(2*x-1)+10*x+1)/(16*sqrt(1-8*x)). a(n) ~ 9*8^(n-2)/sqrt(Pi*n). - Ilya Gutkovskiy, Nov 26 2016 MAPLE a:= proc(n) option remember; `if`(n<3, n^2,       (9*n-2)*(8*n-12)*a(n-1)/((9*n-11)*n))     end: seq(a(n), n=0..30);  # Alois P. Heinz, Nov 26 2016 MATHEMATICA CoefficientList[Series[(Sqrt[1 - 8 x] (2 x - 1) + 10 x + 1) / (16 Sqrt[1 - 8 x]), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 26 2016 *) a[n_] := Binomial[2n-3, n-1] Hypergeometric2F1[1-n, n+1, n-1, -1]; a[0]=0; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Apr 03 2017 *) PROG (Maxima) taylor((sqrt(1-8*x)*(2*x-1)+10*x+1)/(16*sqrt(1-8*x)), x, 0, 10); a(n):=sum(binomial(n+k, n)*binomial(2*n-3, n-k-1), k, 0, n); (PARI) a(n)=sum(k=0, n, binomial(n+k, n)*binomial(2*n-3, n-k-1)) \\ Michel Marcus, Nov 27 2016 CROSSREFS Sequence in context: A175255 A081068 A163072 * A140177 A034494 A084210 Adjacent sequences:  A278686 A278687 A278688 * A278690 A278691 A278692 KEYWORD nonn AUTHOR Vladimir Kruchinin, Nov 26 2016 STATUS approved

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

Last modified October 20 15:10 EDT 2019. Contains 328267 sequences. (Running on oeis4.)