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A183039
a(n) = A051064(n)*3^A051064(n) where A051064(n) equals the 3-adic valuation of 3n.
2
3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 324, 3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 324, 3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 81, 3, 3, 18, 3, 3, 18, 3, 3, 1215, 3, 3, 18, 3, 3, 18, 3, 3, 81
OFFSET
1,1
COMMENTS
3^A051064(n) exactly divides 3n.
LINKS
FORMULA
Logarithmic derivative of A183038.
EXAMPLE
L.g.f.: A(x) = 3*x + 3*x^2/2 + 18*x^3/3 + 3*x^4/4 + 3*x^5/5 + 18*x^6/6 + 3*x^7/7 + 3*x^8/8 + 81*x^9/9 + 3*x^10/10 + 3*x^11/11 + 18*x^12/12 +...
The g.f. of A183038 begins:
exp(A(x)) = 1 + 3*x + 6*x^2 + 15*x^3 + 30*x^4 + 51*x^5 + 93*x^6 +...
PROG
(PARI) {a(n)=valuation(3*n, 3)*3^valuation(3*n, 3)}
CROSSREFS
Sequence in context: A215076 A095106 A130184 * A192527 A227773 A346380
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 19 2010
STATUS
approved