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.

A010531 Decimal expansion of square root of 79.

Original entry on oeis.org

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

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Comments

Continued fraction expansion is 8 followed by {1, 7, 1, 16} repeated. - Harry J. Smith, Jun 09 2009

Examples

			8.888194417315588850091441675408727817076450603729526298354720116376100...
		

Crossrefs

Cf. A010157 Continued fraction.

Programs

  • Mathematica
    RealDigits[N[Sqrt[79],200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Feb 04 2012 *)
  • PARI
    { default(realprecision, 20080); x=sqrt(79); for (n=1, 20000, d=floor(x); x=(x-d)*10; write("b010531.txt", n, " ", d)); } \\ Harry J. Smith, Jun 09 2009

A041141 Denominators of continued fraction convergents to sqrt(79).

Original entry on oeis.org

1, 1, 8, 9, 152, 161, 1279, 1440, 24319, 25759, 204632, 230391, 3890888, 4121279, 32739841, 36861120, 622517761, 659378881, 5238169928, 5897548809, 99598950872, 105496499681, 838074448639, 943570948320, 15935209621759, 16878780570079
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Magma
    I:=[1,1,8,9,152,161,1279,1440]; [n le 8 select I[n] else 160*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 11 2013
  • Mathematica
    Denominator/@Convergents[Sqrt[79], 50] (* Vladimir Joseph Stephan Orlovsky, Jul 05 2011 *)
    CoefficientList[Series[-(x^2 - x - 1) (x^4 + 9 x^2 + 1)/(x^8 - 160 x^4 + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 11 2013 *)
    LinearRecurrence[{0,0,0,160,0,0,0,-1},{1,1,8,9,152,161,1279,1440},40] (* Harvey P. Dale, Aug 09 2021 *)

Formula

G.f.: -(x^2-x-1)*(x^4+9*x^2+1) / (x^8-160*x^4+1). - Colin Barker, Nov 13 2013
a(n) = 160*a(n-4) - a(n-8). - Vincenzo Librandi, Dec 11 2013
Showing 1-2 of 2 results.