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.

A016579 Decimal expansion of log(5/2).

Original entry on oeis.org

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

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Examples

			0.916290731874155065183527211768011071450101219908262467791967881980785...
		

Crossrefs

Cf. A016530 (continued fraction).

Programs

  • Magma
    SetDefaultRealField(RealField(100)); Log(5/2); // Vincenzo Librandi, Apr 07 2020
  • Mathematica
    RealDigits[Log[5/2], 10, 120][[1]] (* Vincenzo Librandi, Apr 07 2020 *)
  • PARI
    default(realprecision, 20080); x=10*log(5/2); for (n=0, 20000, d=floor(x); x=(x-d)*10; write("b016579.txt", n, " ", d)); \\ Harry J. Smith, May 25 2009
    

Formula

Equals A016628 minus A002162. - R. J. Mathar, Jan 23 2009
log(5/2) = 2*Sum_{n >= 1} 1/(n*P(n, 7/3)*P(n-1, 7/3)), where P(n, x) denotes the n-th Legendre polynomial. The first 20 terms of the series gives the approximation log(5/2) = 0.916290731874155065183527(19...), correct to 24 decimal places. - Peter Bala, Mar 18 2024

Extensions

Leading zero removed and offset adjusted by R. J. Mathar, Feb 06 2009