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 A041305 Denominators of continued fraction convergents to sqrt(165). 2
 1, 1, 6, 13, 71, 84, 2087, 2171, 12942, 28055, 153217, 181272, 4503745, 4685017, 27928830, 60542677, 330642215, 391184892, 9719079623, 10110264515, 60270402198, 130651068911, 713525746753, 844176815664, 20973769322689, 21817946138353 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,2158,0,0,0,0,0,-1). FORMULA G.f.: -(x^10 -x^9 +6*x^8 -13*x^7 +71*x^6 -84*x^5 -71*x^4 -13*x^3 -6*x^2 -x -1) / ((x^4 -13*x^2 +1)*(x^8 +13*x^6 +168*x^4 +13*x^2 +1)). - Colin Barker, Nov 15 2013 a(n) = 2158*a(n-6) - a(n-12). - Vincenzo Librandi, Dec 15 2013 MATHEMATICA Denominator[Convergents[Sqrt[165], 30]] (* Vincenzo Librandi, Dec 15 2013 *) PROG (MAGMA) I:=[1, 1, 6, 13, 71, 84, 2087, 2171, 12942, 28055, 153217, 181272]; [n le 12 select I[n] else 2158*Self(n-6)-Self(n-12): n in [1..40]]; // Vincenzo Librandi, Dec 15 2013 CROSSREFS Cf. A041304, A010213, A178592. Sequence in context: A177175 A301605 A119110 * A215755 A144535 A042641 Adjacent sequences:  A041302 A041303 A041304 * A041306 A041307 A041308 KEYWORD nonn,frac,easy AUTHOR EXTENSIONS More terms from Colin Barker, Nov 15 2013 STATUS approved

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Last modified May 8 09:21 EDT 2021. Contains 343666 sequences. (Running on oeis4.)