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A135760
Least number in A001764 divisible by 3^n: a(n) = A001764(3^n-1).
0
1, 3, 43263, 6568517413771094628, 748787983804424579516665098357127267955239740580277791815018327
OFFSET
0,2
COMMENTS
Only numbers in A001764 not divisible by 3 are: A001764((3^n-1)/2) for n>=0.
FORMULA
a(n) = C(3^(n+1)-3, 3^n-1) / (2*3^n-1).
MATHEMATICA
Table[Binomial[3^(n + 1) - 3, 3^n - 1]/(2*3^n - 1), {n, 0, 10}] (* G. C. Greubel, Nov 07 2016 *)
PROG
(PARI) a(n)=binomial(3^(n+1)-3, 3^n-1)/(2*3^n-1)
CROSSREFS
Sequence in context: A068161 A116313 A140656 * A003541 A086829 A190722
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 02 2007
STATUS
approved