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A041723 Denominators of continued fraction convergents to sqrt(381). 2
1, 1, 2, 25, 27, 52, 2003, 2055, 4058, 50751, 54809, 105560, 4066089, 4171649, 8237738, 103024505, 111262243, 214286748, 8254158667, 8468445415, 16722604082, 209139694399, 225862298481, 435001992880, 16755938027921, 17190940020801, 33946878048722 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

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

G.f.: -(x^4-x^3+2*x^2+x+1)*(x^6-26*x^3-1) / (x^12-2030*x^6+1). - Colin Barker, Nov 22 2013

a(n) = 2030*a(n-6) - a(n-12) for n>11. - Vincenzo Librandi, Dec 23 2013

MAPLE

convert(sqrt(381), confrac, 30, cvgts): denom(cvgts); # Wesley Ivan Hurt, Dec 23 2013

MATHEMATICA

Denominator[Convergents[Sqrt[381], 30]] (* Vincenzo Librandi, Dec 23 2013 *)

PROG

(MAGMA) I:=[1, 1, 2, 25, 27, 52, 2003, 2055, 4058, 50751, 54809, 105560]; [n le 12 select I[n] else 2030*Self(n-6)-Self(n-12): n in [1..40]]; // Vincenzo Librandi, Dec 23 2013

CROSSREFS

Cf. A041722, A040361.

Sequence in context: A092045 A317886 A054283 * A067443 A163497 A264118

Adjacent sequences:  A041720 A041721 A041722 * A041724 A041725 A041726

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Colin Barker, Nov 22 2013

STATUS

approved

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Last modified October 19 08:16 EDT 2021. Contains 348074 sequences. (Running on oeis4.)