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A041407
Denominators of continued fraction convergents to sqrt(218).
2
1, 1, 4, 13, 17, 489, 506, 2007, 6527, 8534, 245479, 254013, 1007518, 3276567, 4284085, 123230947, 127515032, 505776043, 1644843161, 2150619204, 61862180873, 64012800077, 253900581104, 825714543389, 1079615124493, 31054938029193, 32134553153686
OFFSET
0,3
LINKS
FORMULA
G.f.: -(x^8-x^7+4*x^6-13*x^5+17*x^4+13*x^3+4*x^2+x+1) / (x^10+502*x^5-1). - Colin Barker, Nov 17 2013
a(n) = 502*a(n-5) + a(n-10) for n>9. - Vincenzo Librandi, Dec 17 2013
MATHEMATICA
Denominator[Convergents[Sqrt[218], 30]] (* Vincenzo Librandi, Dec 17 2013 *)
LinearRecurrence[{0, 0, 0, 0, 502, 0, 0, 0, 0, 1}, {1, 1, 4, 13, 17, 489, 506, 2007, 6527, 8534}, 30] (* Harvey P. Dale, Jul 26 2014 *)
PROG
(Magma) I:=[1, 1, 4, 13, 17, 489, 506, 2007, 6527, 8534]; [n le 10 select I[n] else 502*Self(n-5)+Self(n-10): n in [1..40]]; // Vincenzo Librandi, Dec 17 2013
CROSSREFS
Sequence in context: A190122 A042713 A154130 * A252976 A065564 A332377
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 17 2013
STATUS
approved