A041177 Denominators of continued fraction convergents to sqrt(98).
1, 1, 9, 10, 189, 199, 1781, 1980, 37421, 39401, 352629, 392030, 7409169, 7801199, 69818761, 77619960, 1466978041, 1544598001, 13823762049, 15368360050, 290454242949, 305822602999, 2737035066941, 3042857669940, 57508473125861, 60551330795801, 541919119492269
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..200
- Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 198, 0, 0, 0, -1).
Crossrefs
Cf. A041176.
Programs
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Magma
I:=[1, 1, 9, 10, 189, 199, 1781, 1980]; [n le 8 select I[n] else 198*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 12 2013
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Mathematica
Denominator[Convergents[Sqrt[98], 30]] (* or *) CoefficientList[Series[(1 + x + 9 x^2 + 10 x^3 - 9 x^4 + x^5 - x^6)/(1 - 198 x^4 + x^8), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 12 2013 *)
Formula
G.f.: (1 +x +9*x^2 +10*x^3 -9*x^4 +x^5 -x^6)/(1 -198*x^4 +x^8). - Vincenzo Librandi, Dec 12 2013
a(n) = 198*a(n-4) - a(n-8). - Vincenzo Librandi, Dec 12 2013
Extensions
More terms from Vincenzo Librandi, Dec 12 2013