OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..50
FORMULA
a(n) = C(n(n+1), n(n+1)/2) / [n(n+1)/2 + 1].
MATHEMATICA
With[{nn=100}, Join[{1}, Pick[CatalanNumber[Range[nn]], Array[ IntegerQ[ (Sqrt[1+8#]-1)/2]&, nn]]]] (* Harvey P. Dale, Sep 24 2011 *)
Table[Binomial[n*(n + 1), n*(n + 1)/2]/(1 + Binomial[n + 1, 2]), {n, 0, 10}] (* G. C. Greubel, Nov 07 2016 *)
PROG
(PARI) a(n)=binomial(n*(n+1), n*(n+1)/2)/(n*(n+1)/2+1)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul D. Hanna, Dec 02 2007
STATUS
approved