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A042218
Numerators of continued fraction convergents to sqrt(635).
2
25, 126, 6325, 31751, 1593875, 8001126, 401650175, 2016252001, 101214250225, 508087503126, 25505589406525, 128036034535751, 6427307316194075, 32264572615506126, 1619655938091500375
OFFSET
0,1
FORMULA
G.f.: (25 +126*x +25*x^2 -x^3)/(x^4 -252*x^2 +1). - Vincenzo Librandi, Nov 19 2013
a(n) = 252*a(n-2) - a(n-4). - Vincenzo Librandi, Nov 19 2013
MATHEMATICA
Numerator[Convergents[Sqrt[635], 30]] (* Harvey P. Dale, Dec 15 2012 *)
CoefficientList[Series[(25 + 126 x + 25 x^2 - x^3)/(x^4 - 252 x^2 + 1), {x, 0, 30}], x](* Vincenzo Librandi, Nov 19 2013 *)
PROG
(Magma) I:=[25, 126, 6325, 31751]; [n le 4 select I[n] else 252*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 19 2013
CROSSREFS
Cf. A042219.
Sequence in context: A201842 A057902 A042216 * A045166 A365872 A232873
KEYWORD
nonn,cofr,frac,easy
AUTHOR
STATUS
approved