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A037078
In ternary expansion of n, reading from right to left, digits occur in order ...,0,1,2,0,1,2,...
3
0, 1, 2, 3, 7, 11, 21, 34, 65, 102, 196, 308, 588, 925, 1766, 2775, 5299, 8327, 15897, 24982, 47693, 74946, 143080, 224840, 429240, 674521, 1287722, 2023563, 3863167, 6070691, 11589501, 18212074, 34768505, 54636222, 104305516, 163908668
OFFSET
0,3
FORMULA
G.f. x*(1+2*x) / ( (x-1)*(1+x+x^2)*(3*x^2-1) ). - R. J. Mathar, Mar 22 2011
a(0)=0, a(1)=1, a(2)=2, a(3)=3, a(4)=7, a(n)=3*a(n-2)+a(n-3)-3*a(n-5). - Harvey P. Dale, Aug 23 2013
EXAMPLE
34 = 1021 (base 3) passes the test.
MATHEMATICA
CoefficientList[Series[x (1+2x)/((x-1)(1+x+x^2)(3x^2-1)), {x, 0, 40}], x] (* or *) LinearRecurrence[{0, 3, 1, 0, -3}, {0, 1, 2, 3, 7}, 40] (* Harvey P. Dale, Aug 23 2013 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman
STATUS
approved