A042261 Denominators of continued fraction convergents to sqrt(656).

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

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: A349785 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