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A033139
Base 3 digits are, in order, the first n terms of the periodic sequence with initial period 1,0,0.
5
1, 3, 9, 28, 84, 252, 757, 2271, 6813, 20440, 61320, 183960, 551881, 1655643, 4966929, 14900788, 44702364, 134107092, 402321277, 1206963831, 3620891493, 10862674480, 32588023440, 97764070320, 293292210961, 879876632883
OFFSET
1,2
FORMULA
G.f.: 1/((1-3*x)*(1-x^3)). - Paul Barry, May 02 2003
a(n) = 3^(n+3)/26 -1/6 +(5*A049347(n)+7*A049347(n-1))/39. - R. J. Mathar, Mar 19 2011
MATHEMATICA
CoefficientList[Series[1/((1-3x)(1-x^3)), {x, 0, 1001}], x] (* Vincenzo Librandi, Apr 04 2012 *)
PROG
(PARI) x='x+O('x^50); Vec(1/((1-3*x)*(1-x^3))) \\ G. C. Greubel, Sep 26 2017
CROSSREFS
Cf. A000975.
Sequence in context: A027099 A292328 A027090 * A372870 A291731 A291257
KEYWORD
nonn,base,easy
STATUS
approved