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A109642
a(n) = least composite m such that binomial(3m,m) mod m = 3^n.
4
4, 15, 57, 765, 1025, 2097, 4947, 9189, 103599, 216927, 4346128, 1558269, 1977777
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
Sequence in context: A371777 A095930 A026850 * A307570 A164589 A377315
KEYWORD
nonn
AUTHOR
Ryan Propper, Aug 05 2005
EXTENSIONS
Edited by Max Alekseyev, Nov 03 2009
STATUS
approved