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 A029548 Expansion of 1/(1-32*x+x^2). 21
 1, 32, 1023, 32704, 1045505, 33423456, 1068505087, 34158739328, 1092011153409, 34910198169760, 1116034330278911, 35678188370755392, 1140585993533893633, 36463073604713840864, 1165677769357309014015 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS From Bruno Berselli, Nov 21 2011: (Start) A Diophantine property of these numbers: ((a(n+1) - a(n-1))/2)^2 - 255*a(n)^2 = 1. More generally, for t(m) = m + sqrt(m^2-1) and u(n) = (t(m)^(n+1) - 1/t(m)^(n+1))/(t(m) - 1/t(m)), we can verify that ((u(n+1) - u(n-1))/2)^2 - (m^2-1)*u(n)^2 = 1. (End) a(n) equals the number of 01-avoiding words of length n on alphabet {0,1,...,31}. - Milan Janjic, Jan 26 2015 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..600 Tanya Khovanova, Recursive Sequences Index entries for linear recurrences with constant coefficients, signature (32,-1). FORMULA a(n) = 32*a(n-1) - a(n-2), a(-1)=0, a(0)=1. a(n) = S(n, 32) with S(n, x) = U(n, x/2) Chebyshev's polynomials of the 2nd kind. See A049310. - Wolfdieter Lang, Nov 29 2002 a(n) = (ap^(n+1) - am^(n+1))/(ap - am) with ap=16+sqrt(255) and am=16-sqrt(255). a(n) = Sum_{k=0..floor(n/2)} (-1)^k*binomial(n-k, k)*32^(n-2*k). a(n) = Sum_{k, 0<=k<=n} A101950(n,k)*31^k. - Philippe Deléham, Feb 10 2012 Product {n >= 0} (1 + 1/a(n)) = 1/15*(15 + sqrt(255)). - Peter Bala, Dec 23 2012 Product {n >= 1} (1 - 1/a(n)) = 1/32*(15 + sqrt(255)). - Peter Bala, Dec 23 2012 MAPLE seq( simplify(ChebyshevU(n, 17)), n=0..20); # G. C. Greubel, Dec 22 2019 MATHEMATICA Table[GegenbauerC[n, 1, 16], {n, 0, 20}] (* Vladimir Joseph Stephan Orlovsky, Sep 11 2008 *) CoefficientList[Series[1/(1-32x+x^2), {x, 0, 20}], x] (* Vincenzo Librandi, Dec 24 2012 *) ChebyshevU[Range[21] -1, 17] (* G. C. Greubel, Dec 22 2019 *) PROG (Sage) [lucas_number1(n, 32, 1) for n in range(1, 16)] # Zerinvary Lajos, Nov 07 2009 (Sage) [chebyshev_U(n, 16) for n in (0..20)] # G. C. Greubel, Dec 22 2019 (MAGMA) I:=[1, 32]; [n le 2 select I[n] else 32*Self(n-1)-Self(n-2): n in [1..20]]; // Vincenzo Librandi, Dec 24 2012 (PARI) vector( 21, n, polchebyshev(n-1, 2, 17) ) \\ G. C. Greubel, Dec 22 2019 (GAP) m:=17;; a:=[1, 2*m];; for n in [3..20] do a[n]:=2*m*a[n-1]-a[n-2]; od; a; # G. C. Greubel, Dec 22 2019 CROSSREFS Cf. A200441, A200442. Chebyshev sequence U(n, m): A000027 (m=1), A001353 (m=2), A001109 (m=3), A001090 (m=4), A004189 (m=5), A004191 (m=6), A007655 (m=7), A077412 (m=8), A049660 (m=9), A075843 (m=10), A077421 (m=11), A077423 (m=12), A097309 (m=13), A097311 (m=14), A097313 (m=15), this sequence (m=16), A029547 (m=17), A144128 (m=18), A078987 (m=19), A097316 (m=33). Sequence in context: A300265 A158617 A171337 * A016745 A189267 A223672 Adjacent sequences:  A029545 A029546 A029547 * A029549 A029550 A029551 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified April 13 00:24 EDT 2021. Contains 342934 sequences. (Running on oeis4.)