A042237 Denominators of continued fraction convergents to sqrt(644).

1, 2, 3, 5, 8, 53, 61, 114, 175, 464, 23375, 47214, 70589, 117803, 188392, 1248155, 1436547, 2684702, 4121249, 10927200, 550481249, 1111889698, 1662370947, 2774260645, 4436631592, 29394050197, 33830681789, 63224731986, 97055413775, 257335559536

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,23550,0,0,0,0,0,0,0,0,0,-1).

Formula

G.f.: -(x^18 -2*x^17 +3*x^16 -5*x^15 +8*x^14 -53*x^13 +61*x^12 -114*x^11 +175*x^10 -464*x^9 -175*x^8 -114*x^7 -61*x^6 -53*x^5 -8*x^4 -5*x^3 -3*x^2 -2*x -1) / (x^20 -23550*x^10 +1). - Colin Barker, Dec 05 2013

Mathematica

Denominator[Convergents[Sqrt[644], 30]] (* Vincenzo Librandi, Jan 18 2014 *)

Crossrefs

Cf. A042236, A040618.

Sequence in context: A042471 A041871 A061249 * A042937 A045504 A068500

Adjacent sequences: A042234 A042235 A042236 * A042238 A042239 A042240

Keyword

nonn,frac,easy

Author

N. J. A. Sloane

Extensions

More terms from Colin Barker, Dec 05 2013

Status

approved