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.

A221711 Decimal expansion of sum 1/(p^2 * log p) over the primes p=2,3,5,7,11,...

Original entry on oeis.org

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

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Author

N. J. A. Sloane, Jan 26 2013

Keywords

Examples

			0.50778218785919931877437510379470557...
		

References

  • Henri Cohen, Number Theory, Volume II: Analytic and Modern Tools, GTM Vol. 240, Springer, 2007; see pp. 208-209.

Crossrefs

Cf. A137245.

Programs

  • Mathematica
    digits = 106; precision = digits + 15;
    tmax = 400; (* integrand considered negligible beyond tmax *)
    kmax = 400; (* f(k) considered negligible beyond kmax *)
    InLogZeta[k_] := NIntegrate[Log[Zeta[t]], {t, k, tmax},
       WorkingPrecision -> precision, MaxRecursion -> 20,
       AccuracyGoal -> precision];
    f[k_] := With[{mu = MoebiusMu[k]}, If[mu == 0, 0, (mu/k^2)*InLogZeta[2k]]];
    s = 0; Do[s = s + f[k]; Print[k, " ", s], {k, 1, kmax}];
    RealDigits[s][[1]][[1 ;; digits]] (* Jean-François Alcover, Feb 06 2021, updated Jun 23 2022 *)
  • PARI
    \\ See Belabas, Cohen link. Run as SumEulerlog(2) after setting the required precision.
    
  • PARI
    default(realprecision, 200); s=0; for(k=1, 300, s = s + moebius(k)/k^2 * intnum(x=2*k,[[1], 1], log(zeta(x))); print(s)); \\ Vaclav Kotesovec, Jun 12 2022

Extensions

More terms from Hugo Pfoertner, Feb 01 2020
More digits from Vaclav Kotesovec, Jun 12 2022