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A042907 Denominators of continued fraction convergents to sqrt(985). 2
1, 2, 3, 5, 13, 811, 1635, 2446, 4081, 10608, 661777, 1334162, 1995939, 3330101, 8656141, 540010843, 1088677827, 1628688670, 2717366497, 7063421664, 440649509665, 888362440994, 1329011950659, 2217374391653, 5763760733965, 359570539897483, 724904840528931 (list; graph; refs; listen; history; text; internal format)
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, 816, 0, 0, 0, 0, 1).

FORMULA

G.f.: -(x^8-2*x^7+3*x^6-5*x^5+13*x^4+5*x^3+3*x^2+2*x+1) / (x^10+816*x^5-1). - Colin Barker, Dec 25 2013

a(n) = 816*a(n-5) + a(n-10) for n>9. - Vincenzo Librandi, Feb 01 2014

MATHEMATICA

Denominator[Convergents[Sqrt[985], 30]] (* Vincenzo Librandi, Feb 01 2014 *)

LinearRecurrence[{0, 0, 0, 0, 816, 0, 0, 0, 0, 1}, {1, 2, 3, 5, 13, 811, 1635, 2446, 4081, 10608}, 30] (* Harvey P. Dale, Jan 01 2017 *)

PROG

(MAGMA) I:=[1, 2, 3, 5, 13, 811, 1635, 2446, 4081, 10608]; [n le 10 select I[n] else 816*Self(n-5)+Self(n-10): n in [1..30]]; // Vincenzo Librandi, Feb 01 2014

CROSSREFS

Cf. A042906, A040953.

Sequence in context: A114747 A041639 A006985 * A115347 A173654 A126333

Adjacent sequences:  A042904 A042905 A042906 * A042908 A042909 A042910

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Dec 25 2013

STATUS

approved

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Last modified May 6 18:38 EDT 2021. Contains 343586 sequences. (Running on oeis4.)