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A042261 Denominators of continued fraction convergents to sqrt(656). 2
1, 1, 2, 3, 5, 13, 18, 31, 49, 80, 4049, 4129, 8178, 12307, 20485, 53277, 73762, 127039, 200801, 327840, 16592801, 16920641, 33513442, 50434083, 83947525, 218329133, 302276658, 520605791, 822882449, 1343488240, 67997294449, 69340782689, 137338077138 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,4098,0,0,0,0,0,0,0,0,0,-1).

FORMULA

G.f.: -(x^4-3*x^3+4*x^2-2*x+1)*(x^4+2*x^3+4*x^2+3*x+1)*(x^10-16*x^5-1) / ((x^10-64*x^5-1)*(x^10+64*x^5-1)). - Colin Barker, Dec 06 2013

MAPLE

convert(sqrt(656), confrac, 30, cvgts): denom(cvgts); # Wesley Ivan Hurt, Dec 07 2013

MATHEMATICA

Denominator[Convergents[Sqrt[656], 30]] (* Harvey P. Dale, Jun 04 2013 *)

PROG

(MAGMA) I:=[1, 1, 2, 3, 5, 13, 18, 31, 49, 80, 4049, 4129, 8178, 12307, 20485, 53277, 73762, 127039, 200801, 327840]; [n le 20 select I[n] else 4098*Self(n-10)-Self(n-20): n in [1..40]]; // Vincenzo Librandi, Jan 19 2014

CROSSREFS

Cf. A042260, A040630.

Sequence in context: A162573 A087356 A281598 * A112596 A179238 A041385

Adjacent sequences:  A042258 A042259 A042260 * A042262 A042263 A042264

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Dec 06 2013

STATUS

approved

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Last modified August 15 16:02 EDT 2020. Contains 336505 sequences. (Running on oeis4.)