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 A004190 Expansion of 1/(1 - 11*x + x^2). 13
 1, 11, 120, 1309, 14279, 155760, 1699081, 18534131, 202176360, 2205405829, 24057287759, 262424759520, 2862615066961, 31226340977051, 340627135680600, 3715672151509549, 40531766530924439, 442133759688659280 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Chebyshev or generalized Fibonacci sequence. This is the m=13 member of the m-family of sequences S(n,m-2) = S(2*n+1,sqrt(m))/sqrt(m). The m=4..12 (nonnegative) sequences are A000027, A001906, A001353, A004254, A001109, A004187, A001090, A018913 and A004189. The m=1..3 (signed) sequences are A049347, A056594, A010892. All positive integer solutions of Pell equation b(n)^2 - 117*a(n)^2 = +4 together with b(n+1)=A057076(n+1), n >= 0. - Wolfdieter Lang, Aug 31 2004 For positive n, a(n) equals the permanent of the tridiagonal matrix of order n with 11's along the main diagonal, and i's along the superdiagonal and the subdiagonal (i is the imaginary unit). - John M. Campbell, Jul 08 2011 a(n) equals the number of 01-avoiding words of length n-1 on alphabet {0,1,...,10}. - Milan Janjic, Jan 25 2015 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..900 Andersen, K., Carbone, L. and Penta, D., Kac-Moody Fibonacci sequences, hyperbolic golden ratios, and real quadratic fields, Journal of Number Theory and Combinatorics, Vol 2, No. 3 pp 245-278, 2011. See Section 9. Hacène Belbachir, Soumeya Merwa Tebtoub, László Németh, Ellipse Chains and Associated Sequences, J. Int. Seq., Vol. 23 (2020), Article 20.8.5. D. Birmajer, J. B. Gil, M. D. Weiner, n the Enumeration of Restricted Words over a Finite Alphabet, J. Int. Seq. 19 (2016) # 16.1.3, example 12 S. Falcon, Generalized Fibonacci Sequences Generated from a k-Fibonacci Sequence, Journal of Mathematics Research Vol. 4, No. 2; April 2012. - From N. J. A. Sloane, Sep 22 2012 R. Flórez, R. A. Higuita, A. Mukherjee, Alternating Sums in the Hosoya Polynomial Triangle, Article 14.9.5 Journal of Integer Sequences, Vol. 17 (2014). A. F. Horadam, Special properties of the sequence W_n(a,b; p,q), Fib. Quart., 5.5 (1967), 424-434. Case a=0,b=1; p=11, q=-1. M. Janjic, On Linear Recurrence Equations Arising from Compositions of Positive Integers, Journal of Integer Sequences, Vol. 18 (2015), Article 15.4.7. Tanya Khovanova, Recursive Sequences W. Lang, On polynomials related to powers of the generating function of Catalan's numbers, Fib. Quart. 38 (2000) 408-419. Eq.(44), lhs, m=13. Index entries for linear recurrences with constant coefficients, signature (11,-1). FORMULA Recursion: a(n) = 11*a(n-1) - a(n-2), n >= 1; a(-1)=0, a(0)=1. a(n) = S(2*n+1, sqrt(13))/sqrt(13) = S(n, 11); S(n, x) := U(n, x/2), Chebyshev polynomials of 2nd kind, A049310. G.f.: 1/(1 - 11*x + x^2). a(n) = ((11+3*sqrt(13))^(n+1) - (11-3*sqrt(13))^(n+1))/(2^(n+1)*3*sqrt(13)). - Rolf Pleisch, May 22 2011 a(n) = Sum_{k=0..n} A101950(n,k)*10^k. - Philippe Deléham, Feb 10 2012 Product_{n>=0} (1 + 1/a(n)) = 1/3*(3 + sqrt(13)). - Peter Bala, Dec 23 2012 Product_{n>=1} (1 - 1/a(n)) = 3/22*(3 + sqrt(13)). - Peter Bala, Dec 23 2012 a(n) = sqrt((A057076(n+1)^2 - 4)/117). a(n) = A075835(n+1)/3 = A006190(2*n+2)/3. - Vladimir Reshetnikov, Sep 16 2016 a(n) = -a(-2-n) for all n in Z. - Michael Somos, Jul 14 2018 EXAMPLE G.f. = 1 + 11*x + 120*x^2 + 1309*x^3 + 14279*x^4 + 155760*x^5 + ... MAPLE with(combinat):seq(fibonacci(2*n+2, 3)/3, n=0..20); # Zerinvary Lajos, Apr 20 2008 MATHEMATICA Join[{a=1, b=11}, Table[c=11*b-a; a=b; b=c, {n, 60}]] (* Vladimir Joseph Stephan Orlovsky, Jan 20 2011 *) CoefficientList[Series[1/(1-11*x+x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jun 13 2012 *) Table[Fibonacci[2n + 2, 3]/3, {n, 0, 20}] (* Vladimir Reshetnikov, Sep 16 2016 *) a[ n_] := ChebyshevU[n, 11/2]; (* Michael Somos, Jul 14 2018 *) PROG (Sage) [lucas_number1(n, 11, 1) for n in range(1, 20)] # Zerinvary Lajos, Jun 25 2008 (PARI) Vec(1/(1-11*x+x^2)+O(x^99)) \\ Charles R Greathouse IV, Sep 23 2012 (PARI) {a(n) = polchebyshev(n, 2, 11/2)}; /* Michael Somos, Jul 14 2018 */ CROSSREFS Cf. A049310, A004189, A057076. Sequence in context: A274119 A171316 A081122 * A089707 A223391 A337707 Adjacent sequences:  A004187 A004188 A004189 * A004191 A004192 A004193 KEYWORD nonn,easy AUTHOR EXTENSIONS Wolfdieter Lang, Oct 31 2002 STATUS approved

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Last modified October 19 21:18 EDT 2021. Contains 348091 sequences. (Running on oeis4.)