OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..300
FORMULA
a(n) is divisible by 5 for gcd(n,5) = 1 and n>0.
a(n) ~ n^(n-1/2) * exp(n-2/3) * 3^n / (sqrt(Pi) * 2^(n+1/2)). - Vaclav Kotesovec, Apr 23 2015
EXAMPLE
a(2) = C(5,2) = 10; a(3) = C(12,3) = 220; a(4) = C(22,4) = 7315; a(5) = C(35,5) = 324632; ...
MATHEMATICA
Table[Binomial[n*(3n-1)/2, n], {n, 0, 20}] (* Harvey P. Dale, Aug 16 2012 *)
PROG
(PARI) {a(n)=binomial(n*(3*n-1)/2, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 09 2011
STATUS
approved