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.

A007514 Pi = Sum_{n >= 0} a(n)/n!.

Original entry on oeis.org

3, 0, 0, 0, 3, 1, 5, 6, 5, 0, 1, 4, 7, 8, 0, 6, 7, 10, 7, 10, 4, 10, 6, 16, 1, 11, 20, 3, 18, 12, 9, 13, 18, 21, 14, 34, 27, 11, 27, 33, 36, 18, 5, 18, 5, 23, 39, 1, 10, 42, 28, 17, 20, 51, 8, 42, 47, 0, 27, 23, 16, 52, 32, 52, 53, 24, 43, 61, 64, 18, 17, 11, 0, 53, 14, 62
Offset: 0

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Keywords

Comments

The current name does not define a(n) without ambiguity. It is meant that for each n, a(n) is the largest integer such that the remainder of Pi - (partial sum up to n) remains positive. This leads to the FORMULA given below. - M. F. Hasler, Mar 20 2017

Examples

			Pi = 3/0! + 0/1! + 0/2! + 0/3! + 3/4! + 1/5! + ...
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Essentially same as A075874.
Pi in base n: A004601 to A004608, A000796, A068436 to A068440, A062964.

Programs

  • Mathematica
    p = N[Pi, 1000]; Do[k = Floor[p*n! ]; p = p - k/n!; Print[k], {n, 0, 75} ]
  • PARI
    x=Pi;vector(floor((y->y/log(y))(default(realprecision))),n,t=(n-1)!;k=floor(x*t);x-=k/t;k) \\ Charles R Greathouse IV, Jul 15 2011
    
  • PARI
    C=1/Pi;x=0;vector(primepi(default(realprecision)),n,-x*n--+x=n!\C) \\ M. F. Hasler, Mar 20 2017

Formula

a(n) = floor(n!*Pi) - n*floor((n-1)!*Pi) for all n > 0. - M. F. Hasler, Mar 20 2017