Voozh

A041766

Numerators of continued fraction convergents to sqrt(404).

20, 201, 8060, 80801, 3240100, 32481801, 1302512140, 13057603201, 523606640180, 5249124005001, 210488566840220, 2110134792407201, 84615880263128260, 848268937423689801, 34015373377210720300, 341002002709530892801, 13674095481758446432340

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (0,402,0,-1).

FORMULA

G.f.: (20 + 201*x + 20*x^2 - x^3)/(1 - 402*x^2 + x^4). - Vincenzo Librandi, Nov 07 2013

a(n) = 402*a(n-2)-a(n-4). - Vincenzo Librandi, Nov 07 2013

MATHEMATICA

Numerator[Convergents[Sqrt[404], 30]] (* or *) CoefficientList[Series[(20 + 201 x + 20 x^2 - x^3)/(1 - 402 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 07 2013 *)

LinearRecurrence[{0, 402, 0, -1}, {20, 201, 8060, 80801}, 20] (* Harvey P. Dale, Oct 27 2018 *)

PROG

(Magma) I:=[20, 201, 8060, 80801]; [n le 4 select I[n] else 402*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 07 2013

CROSSREFS

Cf. A041767.

Sequence in context: A120787 A223753 A099197 * A121088 A302838 A302921

Adjacent sequences: A041763 A041764 A041765 * A041767 A041768 A041769

KEYWORD

nonn,frac,easy,less

AUTHOR

N. J. A. Sloane

STATUS

approved

URL: https://oeis.org/A041766

⇱ A041766 - OEIS