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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A026032 a(n) = C(3n,n) - C(3n,n-4). 0
1, 3, 15, 84, 494, 2988, 18411, 114950, 724845, 4606095, 29451240, 189264672, 1221417360, 7910510312, 51388786107, 334716829674, 2185180379179, 14294808917025, 93680975707935, 614925987859260, 4042236129950970 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: (2*g-1)*(2*g^2-2*g+1)/((3*g-1)*(g-1)^4) where g*(1-g)^2 = x. - Mark van Hoeij, Nov 09 2011
MATHEMATICA
Table[Binomial[3n, n]-Binomial[3n, n-4], {n, 0, 20}] (* Harvey P. Dale, Dec 14 2012 *)
PROG
(PARI) a(n) = binomial(3*n, n) - binomial(3*n, n-4); \\ Michel Marcus, May 10 2020
CROSSREFS
a(n) = T(3n, n), where T is defined in A026022.
Sequence in context: A355094 A106569 A260769 * A005809 A067122 A202336
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Ralf Stephan, Jan 09 2005
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 11:14 EDT 2024. Contains 371278 sequences. (Running on oeis4.)