OFFSET
1,1
COMMENTS
Subsequence of A109641.
MATHEMATICA
In[1]:= n = 1; Do[If[ !PrimeQ[k] && Mod[Binomial[3*k, k], k] == 3^n, Print[k]; n++ ], {k, 1, 10^4}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ryan Propper, Aug 05 2005
EXTENSIONS
Edited by Max Alekseyev, Nov 03 2009
STATUS
approved