login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A041775 Denominators of continued fraction convergents to sqrt(408). 2
1, 5, 201, 1010, 40601, 204015, 8201201, 41210020, 1656602001, 8324220025, 334625403001, 1681451235030, 67592674804201, 339644825256035, 13653385685045601, 68606573250484040, 2757916315704407201, 13858188151772520045, 557085442386605209001 (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 (0,202,0,-1).

FORMULA

G.f.: -(x^2-5*x-1) / (x^4-202*x^2+1). - Colin Barker, Nov 24 2013

a(n) = 202*a(n-2) - a(n-4). for n>3. - Vincenzo Librandi, Dec 24 2013

MATHEMATICA

Denominator[Convergents[Sqrt[408], 30]] (* Vincenzo Librandi, Dec 24 2013 *)

PROG

(Magma) I:=[1, 5, 201, 1010]; [n le 4 select I[n] else 202*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 24 2013

CROSSREFS

Cf. A041774, A040387.

Sequence in context: A128791 A303136 A244848 * A093976 A337579 A196799

Adjacent sequences: A041772 A041773 A041774 * A041776 A041777 A041778

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 24 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 19:36 EST 2022. Contains 358703 sequences. (Running on oeis4.)