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 A077424 Chebyshev sequence T(n,12) with Diophantine property. 5
 1, 12, 287, 6876, 164737, 3946812, 94558751, 2265463212, 54276558337, 1300371936876, 31154649926687, 746411226303612, 17882714781360001, 428438743526336412, 10264647129850713887, 245923092372890796876 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(143+286k)-1 and a(143+286k)+1 are consecutive odd powerful numbers. See A076445. - T. D. Noe, May 04 2006 Except for the first term, positive values of x (or y) satisfying x^2 - 24xy + y^2 + 143 = 0. - Colin Barker, Feb 19 2014 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 Tanya Khovanova, Recursive Sequences Index entries for linear recurrences with constant coefficients, signature (24,-1). FORMULA a(n+1)^2 - 143*b(n)^2 = 1 for n>=0, with the companion sequence b(n)=A077423(n). a(n) = 24*a(n-1) - a(n-2) for n>0, a(-1) := 12, a(0)=1. a(n) = T(n, 12)= (S(n, 24)-S(n-2, 24))/2 = S(n, 24)-11*S(n-1, 24) with T(n, x), resp. S(n, x), Chebyshev's polynomials of the first, resp. second, kind. See A053120 and A049310. S(n, 24)=A077423(n). a(n) = (ap^n + am^n)/2, with ap := 12+sqrt(143) and am := 12-sqrt(143). a(n) = sum( ((-1)^k)*(n/(2*(n-k)))*binomial(n-k, k)*(2*12)^(n-2*k), k=0..floor(n/2) ) for n>=1. a(n+1) = sqrt(1 + 143*A077423(n)^2) for n>=0. G.f.: (1-12*x)/(1-24*x+x^2). MATHEMATICA CoefficientList[Series[(1 - 12 x)/(1 - 24 x + x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Feb 21 2014 *) PROG (Sage) [lucas_number2(n, 24, 1)/2 for n in xrange(0, 20)] - Zerinvary Lajos, Jun 26 2008 (PARI) Vec((1-12*x)/(1-24*x+x^2) + O(x^100)) \\ Colin Barker, Feb 19 2014 (MAGMA) I:=[1, 12]; [n le 2 select I[n] else 24*Self(n-1)-Self(n-2): n in [1..20]]; // Vincenzo Librandi, Feb 21 2014 CROSSREFS Cf. A090732. Sequence in context: A079519 A275007 A262733 * A275562 A275087 A267670 Adjacent sequences:  A077421 A077422 A077423 * A077425 A077426 A077427 KEYWORD nonn,easy AUTHOR Wolfdieter Lang, Nov 29 2002 STATUS approved

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Last modified November 21 05:01 EST 2017. Contains 294988 sequences.