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A041722 Numerators of continued fraction convergents to sqrt(381). 2
19, 20, 39, 488, 527, 1015, 39097, 40112, 79209, 990620, 1069829, 2060449, 79366891, 81427340, 160794231, 2010958112, 2171752343, 4182710455, 161114749633, 165297460088, 326412209721, 4082243976740, 4408656186461, 8490900163201, 327062862388099 (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, 0, 0, 0, 0, 2030, 0, 0, 0, 0, 0, -1).

FORMULA

a(n) = 2030*a(n-6) - a(n-12) for n>11. [Bruno Berselli, Nov 07 2013]

G.f.: -(x^11 -19*x^10 +20*x^9 -39*x^8 +488*x^7 -527*x^6 -1015*x^5 -527*x^4 -488*x^3 -39*x^2 -20*x -19) / (x^12 -2030*x^6 +1). - Colin Barker, Dec 28 2013

MATHEMATICA

Numerator[Convergents[Sqrt[381], 30]] (* Harvey P. Dale, Mar 26 2013 *)

PROG

(MAGMA) I:=[19, 20, 39, 488, 527, 1015, 39097, 40112, 79209, 990620, 1069829, 2060449]; [n le 12 select I[n] else 2030*Self(n-6)-Self(n-12): n in [1..30]]; // Bruno Berselli, Nov 07 2013

CROSSREFS

Cf. A041723, A040361.

Sequence in context: A041728 A041726 A041724 * A041738 A041740 A041736

Adjacent sequences:  A041719 A041720 A041721 * A041723 A041724 A041725

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Dec 28 2013

STATUS

approved

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Last modified September 27 11:57 EDT 2021. Contains 347689 sequences. (Running on oeis4.)