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A041581
Denominators of continued fraction convergents to sqrt(308).
2
1, 1, 2, 9, 11, 20, 691, 711, 1402, 6319, 7721, 14040, 485081, 499121, 984202, 4435929, 5420131, 9856060, 340526171, 350382231, 690908402, 3114015839, 3804924241, 6918940080, 239048886961, 245967827041, 485016714002, 2186034683049, 2671051397051
OFFSET
0,3
LINKS
FORMULA
G.f.: -(x^4 -x^3 +2*x^2 +x +1)*(x^6 -10*x^3 -1) / ((x^4 -9*x^2 +1)*(x^8 +9*x^6 +80*x^4 +9*x^2 +1)). - Colin Barker, Nov 19 2013
a(n) = 702*a(n-6) - a(n-12) for n>11. - Vincenzo Librandi, Dec 20 2013
MATHEMATICA
Denominator[Convergents[Sqrt[308], 30]] (* Harvey P. Dale, Nov 25 2011 *)
CoefficientList[Series[-(x^4 - x^3 + 2 x^2 + x + 1) (x^6 - 10 x^3 - 1)/((x^4 - 9 x^2 + 1) (x^8 + 9 x^6 + 80 x^4 + 9 x^2 + 1)), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 20 2013 *)
PROG
(Magma) I:=[1, 1, 2, 9, 11, 20, 691, 711, 1402, 6319, 7721, 14040]; [n le 12 select I[n] else 702*Self(n-6)-Self(n-12): n in [1..40]]; // Vincenzo Librandi, Dec 20 2013
CROSSREFS
Sequence in context: A131140 A022114 A041099 * A042463 A081613 A115911
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 19 2013
STATUS
approved