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 A001882 a(2n) = a(2n-1) + 2a(2n-2), a(2n+1) = a(2n) + a(2n-1), with a(1) = 2 and a(2) = 3. (Formerly M0730 N0273) 2
 2, 3, 5, 11, 16, 38, 54, 130, 184, 444, 628, 1516, 2144, 5176, 7320, 17672, 24992, 60336, 85328, 206000, 291328, 703328, 994656, 2401312, 3395968, 8198592, 11594560, 27991744, 39586304, 95569792, 135156096, 326295680, 461451776, 1114043136, 1575494912 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS T. D. Noe, Table of n, a(n) for n = 1..500 Michael Fried et al., Problem E1738, Amer. Math. Monthly, 72 (1965), 1024-1025. Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992. Simon Plouffe, 1031 Generating Functions and Conjectures, Université du Québec à Montréal, 1992. Index entries for linear recurrences with constant coefficients, signature (0, 4, 0, -2). FORMULA G.f.: see Maple program. MAPLE A001882:=-(-2-3*z+3*z**2+z**3)/(1-4*z**2+2*z**4); # [Simon Plouffe in his 1992 dissertation for offset 0.] MATHEMATICA a[1] = 2; a[2] = 3; a[n_] := a[n] = If[EvenQ[n], a[n-1] + 2*a[n-2], a[n-1] + a[n-2]]; Table[a[n], {n, 50}] (* T. D. Noe, Aug 10 2012 *) PROG (PARI) x='x+O('x^50); Vec((2+3*x-3*x^2-x^3)/(1-4*x^2+2*x^4)) \\ G. C. Greubel, Aug 13 2017 CROSSREFS Cf. A161941 (bisection). Sequence in context: A316467 A282238 A004690 * A044042 A175179 A040060 Adjacent sequences:  A001879 A001880 A001881 * A001883 A001884 A001885 KEYWORD nonn AUTHOR EXTENSIONS Removed the attribute "conjectured" from the Plouffe g.f. R. J. Mathar, Aug 17 2009 STATUS approved

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Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)