A042229 Denominators of continued fraction convergents to sqrt(640).

1, 3, 7, 10, 47, 57, 674, 731, 3598, 4329, 12256, 41097, 2067106, 6242415, 14551936, 20794351, 97729340, 118523691, 1401489941, 1520013632, 7481544469, 9001558101, 25484660671, 85455540114, 4298261666371, 12980240539227, 30258742744825, 43238983284052

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,2079362,0,0,0,0,0,0,0,0,0,0,0,-1).

Formula

G.f.: -(x^22 - 3*x^21 + 7*x^20 - 10*x^19 + 47*x^18 - 57*x^17 + 674*x^16 - 731*x^15 + 3598*x^14 - 4329*x^13 + 12256*x^12 - 41097*x^11 - 12256*x^10 - 4329*x^9 - 3598*x^8 - 731*x^7 - 674*x^6 - 57*x^5 - 47*x^4 - 10*x^3 - 7*x^2 - 3*x - 1) / ((x^6 - 38*x^3 + 1)*(x^6 + 38*x^3 + 1)*(x^12 + 1442*x^6 + 1)). - Colin Barker, Dec 04 2013

Mathematica

Denominator[Convergents[Sqrt[640], 30]] (* Vincenzo Librandi, Jan 17 2014 *)

Crossrefs

Cf. A042228, A040614.

Sequence in context: A041783 A041899 A101397 * A042373 A265686 A042775

Adjacent sequences: A042226 A042227 A042228 * A042230 A042231 A042232

Keyword

nonn,frac,easy

Author

N. J. A. Sloane

Extensions

More terms from Colin Barker, Dec 04 2013

Status

approved