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A068219 Denominators of coefficients in log(1+x)*(1+x)^(1/3) power series. 2
3, 3, 9, 3, 15, 9, 21, 6, 27, 15, 33, 9, 39, 21, 45, 12, 51, 27, 57, 15, 63, 33, 69, 18, 75, 39, 81, 21, 87, 45, 93, 24, 99, 51, 105, 27, 111, 57, 117, 30, 123, 63, 129, 33, 135, 69, 141, 36, 147, 75, 153, 39, 159, 81, 165, 42, 171, 87, 177, 45, 183, 93, 189, 48, 195, 99 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

log(1+x)*(1+x)^(1/3) = (-4)*sum(k=>1,(-x)^k/(3k))

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = 3*n if n==1 or 3 (mod 4), a(n) = 3*n/2 if n==2 (mod 4), a(n) = 3*n/4 if n==0 (mod 4).

a(n) = 3*A060819(n). - Mitch Harris, Jun 29 2005

MATHEMATICA

fn[n_]:=Module[{m=Mod[n, 4]}, Which[OddQ[m], 3n, m==2, 3 n/2, True, 3 n/4]]; Array[fn, 70] (* Harvey P. Dale, Sep 18 2012 *)

CROSSREFS

Sequence in context: A217883 A036553 A166466 * A157031 A113213 A088032

Adjacent sequences:  A068216 A068217 A068218 * A068220 A068221 A068222

KEYWORD

easy,frac,nonn

AUTHOR

Benoit Cloitre, Mar 30 2002

STATUS

approved

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Last modified October 17 11:47 EDT 2019. Contains 328108 sequences. (Running on oeis4.)