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A042232 Numerators of continued fraction convergents to sqrt(642). 2
25, 51, 76, 1875, 1951, 5777, 290801, 587379, 878180, 21663699, 22541879, 66747457, 3359914729, 6786576915, 10146491644, 250302376371, 260448868015, 771200112401, 38820454488065, 78412109088531 (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 (0,0,0,0,0,11554,0,0,0,0,0,-1).

FORMULA

G.f.: (25 +51*x +76*x^2 +1875*x^3 +1951*x^4 +5777*x^5 +1951*x^6 -1875*x^7 +76*x^8 -51*x^9 +25*x^10 -x^11)/(1 -11554*x^6 +x^12). - Vincenzo Librandi, Nov 19 2013

a(n) = 11554*a(n-6) - a(n-12). - Vincenzo Librandi, Nov 19 2013

MATHEMATICA

Numerator[Convergents[Sqrt[642], 30]] (* or *) CoefficientList[Series[(25 + 51 x + 76 x^2 + 1875 x^3 + 1951 x^4 + 5777 x^5 + 1951 x^6 - 1875 x^7 + 76 x^8 - 51 x^9 + 25 x^10 - x^11)/(1 - 11554 x^6 + x^12), {x, 0, 20}], x] (* Vincenzo Librandi, Nov 19 2013 *)

PROG

(MAGMA) I:=[25, 51, 76, 1875, 1951, 5777, 290801, 587379, 878180, 21663699, 22541879, 66747457]; [n le 12 select I[n] else 11554*Self(n-6)-Self(n-12): n in [1..30]]; // Vincenzo Librandi, Nov 19 2013

CROSSREFS

Cf. A042233.

Sequence in context: A042236 A042238 A042234 * A273868 A270693 A042240

Adjacent sequences:  A042229 A042230 A042231 * A042233 A042234 A042235

KEYWORD

nonn,cofr,frac,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 23 02:43 EST 2018. Contains 299473 sequences. (Running on oeis4.)