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A041945 Denominators of continued fraction convergents to sqrt(495). 2
1, 4, 177, 712, 31505, 126732, 5607713, 22557584, 998141409, 4015123220, 177663563089, 714669375576, 31623116088433, 127207133729308, 5628737000177985, 22642155134441248, 1001883562915592897, 4030176406796812836, 178329645461975357681, 717348758254698243560 (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 (0,178,0,-1).

FORMULA

G.f.: -(x^2-4*x-1) / (x^4-178*x^2+1). - Colin Barker, Nov 27 2013

a(n) = 178*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 27 2013

MATHEMATICA

Denominator[Convergents[Sqrt[495], 30]] (* Harvey P. Dale, Aug 22 2013 *)

CoefficientList[Series[(1 + 4 x - x^2)/(x^4 - 178 x^2 + 1), {x, 0, 40}], x] (* Vincenzo Librandi, Dec 27 2013 *)

PROG

(MAGMA) I:=[1, 4, 177, 712]; [n le 4 select I[n] else 178*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 27 2013

CROSSREFS

Cf. A041944, A040472.

Sequence in context: A113254 A210780 A127606 * A300387 A082393 A176351

Adjacent sequences:  A041942 A041943 A041944 * A041946 A041947 A041948

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 27 2013

STATUS

approved

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Last modified August 7 22:19 EDT 2020. Contains 336279 sequences. (Running on oeis4.)