login
A003478
Expansion of 1/((1-2*x)*(1-x-2*x^3)).
(Formerly M2662)
1
1, 3, 7, 17, 39, 85, 183, 389, 815, 1693, 3495, 7173, 14655, 29837, 60567, 122645, 247855, 500061, 1007495, 2027493, 4076191, 8188333, 16437623, 32978613, 66132495, 132562173, 265628263, 532110981, 1065670783, 2133798221, 4271762007, 8550587221, 17113150959
OFFSET
0,2
REFERENCES
D. E. Daykin and S. J. Tucker, Introduction to Dragon Curves. Unpublished, 1976. See links in A003229 for an earlier version.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992.
FORMULA
G.f.: 1/((1-2*x)*(1-x-2*x^3)).
MAPLE
A003478:=1/(2*z-1)/(-1+z+2*z**3); # Conjectured by Simon Plouffe in his 1992 dissertation
MATHEMATICA
CoefficientList[Series[1/((1-2x)(1-x-2x^3)), {x, 0, 50}], x] (* Harvey P. Dale, Mar 14 2011 *)
PROG
(PARI) Vec(1/((1-2*x)*(1-x-2*x^3))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
CROSSREFS
Sequence in context: A319003 A141199 A368655 * A119587 A127984 A157029
KEYWORD
nonn,easy
EXTENSIONS
More terms from Harvey P. Dale, Mar 14 2011
STATUS
approved