cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A010535 Decimal expansion of square root of 84.

Original entry on oeis.org

9, 1, 6, 5, 1, 5, 1, 3, 8, 9, 9, 1, 1, 6, 8, 0, 0, 1, 3, 1, 7, 6, 0, 9, 4, 3, 8, 7, 4, 5, 6, 0, 1, 6, 9, 7, 7, 9, 6, 8, 9, 1, 3, 1, 5, 3, 5, 3, 5, 9, 4, 3, 8, 0, 5, 2, 1, 4, 4, 8, 4, 2, 4, 7, 8, 1, 3, 7, 3, 6, 8, 5, 1, 0, 9, 5, 5, 4, 1, 7, 7, 3, 2, 0, 8, 7, 2, 3, 1, 1, 8, 9, 8, 6, 8, 9, 0, 0, 6
Offset: 1

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Comments

Continued fraction expansion is 9 followed by {6, 18} repeated. - Harry J. Smith, Jun 10 2009

Examples

			9.165151389911680013176094387456016977968913153535943805214484247813736...
		

Crossrefs

Cf. A040074 Continued fraction.

Programs

  • Mathematica
    RealDigits[N[84^(1/2),200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Jan 23 2012 *)
  • PARI
    { default(realprecision, 20080); x=sqrt(84); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b010535.txt", n, " ", d)); } \\ Harry J. Smith, Jun 10 2009

A041149 Denominators of continued fraction convergents to sqrt(84).

Original entry on oeis.org

1, 6, 109, 660, 11989, 72594, 1318681, 7984680, 145042921, 878242206, 15953402629, 96598657980, 1754729246269, 10624974135594, 193004263686961, 1168650556257360, 21228714276319441, 128540936214174006, 2334965566131451549, 14138334333002883300
Offset: 0

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Author

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Crossrefs

Programs

  • Magma
    I:=[1, 6, 109, 660]; [n le 4 select I[n] else 110*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 11 2013
  • Mathematica
    Denominator/@Convergents[Sqrt[84], 50] (* Vladimir Joseph Stephan Orlovsky, Jul 05 2011 *)
    CoefficientList[Series[(1 + 6 x - x^2)/(x^4 - 110 x^2 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 11 2013 *)

Formula

G.f.: -(x^2-6*x-1) / (x^4-110*x^2+1). - Colin Barker, Nov 13 2013
a(n) = 110*a(n-2) - a(n-4). - Vincenzo Librandi, Dec 11 2013
Showing 1-2 of 2 results.