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 A041768 Numerators of continued fraction convergents to sqrt(405). 2
 20, 161, 6460, 51841, 2080100, 16692641, 669785740, 5374978561, 215668928180, 1730726404001, 69444725088220, 557288527109761, 22360985809478660, 179445175002939041, 7200167985927040300, 57780789062419261441, 2318431730482697497940, 18605234632923999244961 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 Index entries for linear recurrences with constant coefficients, signature (0,322,0,-1). FORMULA G.f.: -(x^3-20*x^2-161*x-20) / ((x^2-18*x+1)*(x^2+18*x+1)). - Vincenzo Librandi, Nov 08 2013, simplified by Colin Barker, Dec 28 2013 a(n) = 322*a(n-2)-a(n-4). - Vincenzo Librandi, Nov 08 2013, simplified by Colin Barker, Dec 28 2013 MATHEMATICA Numerator[Convergents[Sqrt[405], 30]] (* Vincenzo Librandi, Nov 07 2013 *) CoefficientList[Series[(20 + 161 x + 6460 x^2 + 51841 x^3 + 6460 x^4 - 161 x^5 + 20 x^6 - x^7)/(1 - 103682 x^4 + x^8), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 08 2013 *) PROG (MAGMA) I:=[20, 161, 6460, 51841, 2080100, 16692641, 669785740, 5374978561]; [n le 8 select I[n] else 103682*Self(n-4)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, Nov 08 2013 CROSSREFS Cf. A041769, A040384. Sequence in context: A126515 A118676 A067534 * A221870 A289181 A056114 Adjacent sequences:  A041765 A041766 A041767 * A041769 A041770 A041771 KEYWORD nonn,frac,easy,less AUTHOR EXTENSIONS More terms from Colin Barker, Dec 28 2013 STATUS approved

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Last modified December 3 05:29 EST 2020. Contains 338899 sequences. (Running on oeis4.)