A135760 Least number in A001764 divisible by 3^n: a(n) = A001764(3^n-1).

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.

Links

Table of n, a(n) for n=0..4.

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

Cf. A001764; A135759.

Sequence in context: A068161 A116313 A140656 * A003541 A086829 A190722

Adjacent sequences: A135757 A135758 A135759 * A135761 A135762 A135763

Keyword

nonn

Author

Paul D. Hanna, Dec 02 2007

Status

approved