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A042886 Numerators of continued fraction convergents to sqrt(975). 2
31, 125, 281, 1249, 77719, 312125, 701969, 3120001, 194142031, 779688125, 1753518281, 7793761249, 484966715719, 1947660624125, 4380287963969, 19468812480001, 1211446661724031, 4865255459376125, 10941957580476281, 48633085781281249 (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 (0,0,0,2498,0,0,0,-1).

FORMULA

G.f.: (31 +125*x +281*x^2 +1249*x^3 +281*x^4 -125*x^5 +31*x^6 -x^7)/(1 -2498*x^4 +x^8). - Vincenzo Librandi, Dec 08 2013

a(n) = 2498*a(n-4) - a(n-8). - Vincenzo Librandi, Dec 08 2013

MATHEMATICA

Numerator[Convergents[Sqrt[975], 30]] (* or *) CoefficientList[Series[(31 + 125 x + 281 x^2 + 1249 x^3 + 281 x^4 - 125 x^5 + 31 x^6 - x^7)/(1 - 2498 x^4 + x^8), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 08 2013 *)

PROG

(MAGMA) I:=[31, 125, 281, 1249, 77719, 312125, 701969, 3120001]; [n le 8 select I[n] else 2498*Self(n-4)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, Dec 08 2013

CROSSREFS

Cf. A042887.

Sequence in context: A131992 A042884 A153073 * A042888 A183836 A078656

Adjacent sequences:  A042883 A042884 A042885 * A042887 A042888 A042889

KEYWORD

nonn,cofr,frac,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Vincenzo Librandi, Dec 08 2013

STATUS

approved

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Last modified February 17 17:12 EST 2019. Contains 320222 sequences. (Running on oeis4.)