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A041867
Denominators of continued fraction convergents to sqrt(455).
2
1, 3, 127, 384, 16255, 49149, 2080513, 6290688, 266289409, 805158915, 34082963839, 103054050432, 4362353081983, 13190113296381, 558347111529985, 1688231447886336, 71464067922756097, 216080435216154627, 9146842347001250431, 27656607476219905920
OFFSET
0,2
FORMULA
G.f.: -(x^2-3*x-1) / (x^4-128*x^2+1). - Colin Barker, Nov 26 2013
a(n) = 128*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 26 2013
MATHEMATICA
Denominator[Convergents[Sqrt[455], 30]] (* Harvey P. Dale, Aug 23 2013 *)
CoefficientList[Series[(1 + 3 x - x^2)/(x^4 - 128 x^2 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 26 2013 *)
PROG
(Magma) I:=[1, 3, 127, 384]; [n le 4 select I[n] else 128*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 26 2013
CROSSREFS
Sequence in context: A142007 A339084 A071151 * A134711 A376466 A163850
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 26 2013
STATUS
approved