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A041315
Denominators of continued fraction convergents to sqrt(171).
2
1, 13, 339, 4420, 115259, 1502787, 39187721, 510943160, 13323709881, 173719171613, 4530022171819, 59064007405260, 1540194214708579, 20081588798616787, 523661502978745041, 6827681127522302320, 178043370818558605361, 2321391501768784172013
OFFSET
0,2
FORMULA
G.f.: -(x^2-13*x-1) / (x^4-340*x^2+1). - Colin Barker, Nov 15 2013
a(n) = 340*a(n-2) - a(n-4). - Vincenzo Librandi, Dec 15 2013
MATHEMATICA
Denominator[Convergents[Sqrt[171], 30]] (* Vincenzo Librandi, Dec 15 2013 *)
LinearRecurrence[{0, 340, 0, -1}, {1, 13, 339, 4420}, 20] (* Harvey P. Dale, Aug 05 2014 *)
PROG
(Magma) I:=[1, 13, 339, 4420]; [n le 4 select I[n] else 340*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 15 2013
CROSSREFS
Sequence in context: A097308 A204195 A238652 * A041312 A372183 A096717
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 15 2013
STATUS
approved