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 A102702 Expansion of (2-x-2*x^2-x^3)/(1-x-x^2)^2. 2
 2, 3, 6, 10, 18, 31, 54, 93, 160, 274, 468, 797, 1354, 2295, 3882, 6554, 11046, 18587, 31230, 52401, 87812, 146978, 245736, 410425, 684818, 1141611, 1901454, 3164458, 5262330, 8744599, 14521158, 24097797, 39965224, 66241330, 109731132 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS A floretion-generated sequence which results from a certain transform of the Fibonacci numbers. Specifically, (a(n)) is the (type 1B) tesfor-transform of the Fibonacci numbers (A000045) with respect to the floretion + .5'i + .5i' Note, for example, that the sequence A001629, appearing in the formula given, has the name "Fibonacci numbers convolved with themselves" and that this sequence arises in FAMP (see program code) under the name: the lesfor-transform (type 1B) of the Fibonacci numbers (A000045) with respect to the floretion + .5'i + .5i' . The denominator of the generating function has roots at the golden ratio phi and -(1+phi). a(n) is the total number of parts not greater than 2 among all compositions of n+3 in which only the last part may be equal to 1. - Andrew Yezhou Wang, Jul 14 2019 REFERENCES Thomas Koshy, Fibonacci and Lucas Numbers with Applications, Chapter 15, page 187, "Hosoya's Triangle". S. Vajda, Fibonacci and Lucas numbers and the Golden Section, Ellis Horwood Ltd., Chichester, 1989, p. 183, Nr.(98). LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 V. E. Hoggatt, Jr. and M. Bicknell-Johnson, Fibonacci convolution sequences, Fib. Quart., 15 (1977), 117-122. Mengmeng Liu and Andrew Yezhou Wang, The number of designated parts in compositions with restricted parts, Journal of Integer Sequences, 23 (2020), Article 20.1.8. Index entries for linear recurrences with constant coefficients, signature (2,1,-2,-1). FORMULA G.f.: (2-x-2*x^2-x^3)/(1-x-x^2)^2. a(n) = 2*F(n+1) + A001629(n+3) - 2*A029907(n+1); F(n+1) = a(n+2) - a(n+1) - a(n). a(0)=2, a(1)=3, a(2)=6, a(3)=10, a(n)=2*a(n-1)+a(n-2)-2*a(n-3)-a(n-4). - Harvey P. Dale, Apr 21 2014 a(n) = A010049(n+1) + A000045(n+2). - R. J. Mathar, May 21 2019 a(n) = ((2*n+10)*F(n+1)-(n-4)*F(n))/5. - Andrew Yezhou Wang, Jul 14 2019 MATHEMATICA CoefficientList[Series[(2-x-2x^2-x^3)/(x^4+2x^3-x^2-2x+1), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 1, -2, -1}, {2, 3, 6, 10}, 40] (* Harvey P. Dale, Apr 21 2014 *) PROG Floretion Algebra Multiplication Program. FAMP Code: (a(n)) = 2tesforseq[ + .5'i + .5i' ], 2lesforseq = A001629, jesforseq = A029907, vesforseq = A000045, ForType: 1B. (Magma) R:=PowerSeriesRing(Integers(), 35); Coefficients(R!( (2-x-2*x^2-x^3)/(1-x-x^2)^2)); // Marius A. Burtea, Dec 31 2019 CROSSREFS Cf. A000045, A001629, A029907. Sequence in context: A347787 A215006 A172516 * A181532 A077930 A060945 Adjacent sequences: A102699 A102700 A102701 * A102703 A102704 A102705 KEYWORD easy,nonn AUTHOR Creighton Dement, Feb 04 2005 EXTENSIONS Corrected by T. D. Noe, Nov 02 2006 STATUS approved

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Last modified March 29 15:25 EDT 2023. Contains 361599 sequences. (Running on oeis4.)