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A003479
Expansion of 1/((1-x)*(1-x-2*x^3)).
(Formerly M0781)
4
1, 2, 3, 6, 11, 18, 31, 54, 91, 154, 263, 446, 755, 1282, 2175, 3686, 6251, 10602, 17975, 30478, 51683, 87634, 148591, 251958, 427227, 724410, 1228327, 2082782, 3531603, 5988258, 10153823, 17217030, 29193547, 49501194, 83935255, 142322350
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 Unpublished, 1976.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
A003476(n+1) + A077949(n)/2 - 1/2. - Ralf Stephan, Sep 25 2004
a(n+1) - a(n) = A077949(n+1). - R. J. Mathar, Mar 22 2011
MAPLE
A003479:=1/(z-1)/(-1+z+2*z**3); # Simon Plouffe in his 1992 dissertation
MATHEMATICA
CoefficientList[Series[1/((1-x)*(1-x-2*x^3)), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 12 2012 *)
PROG
(PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -2, 2, -1, 2]^n*[1; 2; 3; 6])[1, 1] \\ Charles R Greathouse IV, Jun 23 2020
CROSSREFS
Cf. A003229.
Sequence in context: A273225 A274621 A291725 * A093367 A054186 A347212
KEYWORD
easy,nonn
EXTENSIONS
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 29 2003
STATUS
approved