A042887 Denominators of continued fraction convergents to sqrt(975).

1, 4, 9, 40, 2489, 9996, 22481, 99920, 6217521, 24970004, 56157529, 249600120, 15531364969, 62375059996, 140281484961, 623500999840, 38797343475041, 155812874900004, 350423093275049, 1557505248000200, 96915748469287449, 389220499125149996, 875356746719587441

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (0,0,0,2498,0,0,0,-1).

Formula

G.f.: -(x^2 - 4*x - 1)*(x^4 + 10*x^2 + 1) / ((x^4 - 50*x^2 + 1)*(x^4 + 50*x^2 + 1)). - Colin Barker, Dec 25 2013

Mathematica

Denominator[Convergents[Sqrt[975], 30]] (* Vincenzo Librandi, Jan 31 2014 *)
LinearRecurrence[{0, 0, 0, 2498, 0, 0, 0, -1}, {1, 4, 9, 40, 2489, 9996, 22481, 99920}, 30] (* Harvey P. Dale, Dec 29 2019 *)

Crossrefs

Cf. A042886, A040943.

Sequence in context: A374939 A013459 A041229 * A053908 A149165 A083859

Adjacent sequences: A042884 A042885 A042886 * A042888 A042889 A042890

Keyword

nonn,frac,easy

Author

N. J. A. Sloane

Extensions

More terms from Colin Barker, Dec 25 2013

Status

approved