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 1-10 of 10 results.

A137245 Decimal expansion of Sum_{p prime} 1/(p * log p).

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Mar 09 2008

Keywords

Comments

Sum_{p prime} 1/(p^s * log p) equals this value here if s=1, equals A221711 if s=2, 0.22120334039... if s=3. See arXiv:0811.4739.
Erdős (1935) proved that for any sequence where no term divides another, the sum of 1/(x log x) is at most some constant C. He conjectures (1989) that C can be taken to be this constant 1.636..., that is, the primes maximize this sum. - Charles R Greathouse IV, Mar 26 2012 [The conjecture has been proved by Lichtman 2022. - Pontus von Brömssen, Jun 23 2022]
Note that sum 1/(p * log p) is almost (a tiny bit less than) 1 + 2/Pi = 1+A060294 = 1.63661977236758... (Why is it so close?) - Daniel Forgues, Mar 26 2012
Sum 1/(p * log p) is quite close to sum 1/n^2 = Pi^2/6 = 1.644934066... (Cf. David C. Ullrich, "Re: What is Sum(1/p log p)?" for why this is so; mentions A115563.) - Daniel Forgues, Aug 13 2012

Examples

			1.63661632335...
		

References

  • Henri Cohen, Number Theory, Volume II: Analytic and Modern Tools, GTM Vol. 240, Springer, 2007; see pp. 208-209.
  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.27.2, p. 186.

Crossrefs

Cf. A000040, A060294, A221711 (p squared), A115563, A319231 (log squared), A319232 (p and log squared), A354952.

Programs

  • Mathematica
    digits = 105;
    precision = digits + 10;
    tmax = 500; (* integrand considered negligible beyond tmax *)
    kmax = 500; (* f(k) considered negligible beyond kmax *)
    InLogZeta[k_] := NIntegrate[Log[Zeta[t]], {t, k, tmax}, WorkingPrecision -> precision, MaxRecursion -> 20];
    f[k_] := With[{mu = MoebiusMu[k]}, If[mu == 0, 0, (mu/k^2)*InLogZeta[k]]];
    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 22 2022 *)
  • PARI
    \\ See Belabas, Cohen link. Run as SumEulerlog(1) after setting the required precision.
    
  • PARI
    default(realprecision, 200); s=0; for(k=1, 500, s = s + moebius(k)/k^2 * intnum(x=k,[[1], 1], log(zeta(x))); print(s)); \\ Vaclav Kotesovec, Jun 12 2022

Formula

Equals Sum_{n>=1} 1/(A000040(n)*log A000040(n)).

Extensions

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

A319231 Decimal expansion of Sum_{p = prime} 1/(p*log(p)^2).

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Sep 14 2018

Keywords

Comments

Computed by expanding the formalism of arXiv:0811.4739 to double integrals over the Riemann zeta function.

Examples

			1/(2*A253191) + 1/(3*A175478) +1/(5*2.59029...) +1/(7*3.7865)+ ... = 1.52097043...
		

Crossrefs

Programs

  • Mathematica
    digits = 105; precision = digits + 10;
    tmax = 500; (* integrand considered negligible beyond tmax *)
    kmax = 500; (* f(k) considered negligible beyond kmax *)
    InLogZeta[k_] := NIntegrate[(t - k) Log[Zeta[t]], {t, k, tmax}, WorkingPrecision -> precision, MaxRecursion -> 20, AccuracyGoal -> precision];
    f[k_] := With[{mu = MoebiusMu[k]}, If[mu == 0, 0, (mu/k^3)*InLogZeta[k]]];
    s = 0;
    Do[s = s + f[k]; Print[k, " ", s], {k, 1, kmax}];
    RealDigits[s][[1]][[1 ;; digits]] (* Jean-François Alcover, Jun 21 2022, after Vaclav Kotesovec *)
  • PARI
    default(realprecision, 200); s=0; for(k=1, 500, s=s+moebius(k)/k^3 * intnum(x=k,[[1], 1],(x-k)*log(zeta(x))); print(s)); \\ Vaclav Kotesovec, Jun 12 2022

Extensions

More digits from Vaclav Kotesovec, Jun 12 2022

A319232 Decimal expansion of Sum_{p = prime} 1/(p*log p)^2.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Sep 14 2018

Keywords

Comments

Obtained by expanding the formalism of arXiv:0811.4739 to double integrals over the Riemann zeta function.

Examples

			1/A016627^2 + 1/A016650^2 + 1/8.047189^2 + ... = 0.637056184074676....
		

Crossrefs

Programs

  • Mathematica
    digits = 106; precision = digits + 10;
    tmax = 500; (* integrand considered negligible beyond tmax *)
    kmax = 300; (* f(k) considered negligible beyond kmax *)
    InLogZeta[k_] := NIntegrate[(t - 2k) Log[Zeta[t]], {t, 2k, tmax}, WorkingPrecision -> precision, MaxRecursion -> 20, AccuracyGoal -> precision];
    f[k_] := With[{mu = MoebiusMu[k]}, If[mu == 0, 0, (mu/k^3)*InLogZeta[k]]];
    s = 0;
    Do[s = s + f[k]; Print[k, " ", s], {k, 1, kmax}];
    RealDigits[s][[1]][[1 ;; digits]] (* Jean-François Alcover, Jun 21 2022, after Vaclav Kotesovec *)
  • PARI
    default(realprecision, 200); s=0; for(k=1, 300, s = s + moebius(k)/k^3 * intnum(x=2*k,[[1], 1], (x-2*k)*log(zeta(x))); print(s)); \\ Vaclav Kotesovec, Jun 12 2022

Extensions

More terms from Vaclav Kotesovec, Jun 12 2022

A354917 Decimal expansion of Sum_{p = primes} 1 / (p * log(p)^3).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Jun 12 2022

Keywords

Examples

			1.8461474193664495...
		

Crossrefs

Programs

  • Mathematica
    digits = 105; precision = digits + 15;
    tmax = 500; (* integrand considered negligible beyond tmax *)
    kmax = 500; (* f(k) considered negligible beyond kmax *)
    InLogZeta[k_] := NIntegrate[(t - k)^2 Log[Zeta[t]], {t, k, tmax}, WorkingPrecision -> precision, MaxRecursion -> 20, AccuracyGoal -> precision];
    f[k_] := With[{mu = MoebiusMu[k]}, If[mu == 0, 0, (mu/(2 k^4))*InLogZeta[k]]];
    s = 0;
    Do[s = s + f[k]; Print[k, " ", s], {k, 1, kmax}];
    RealDigits[s][[1]][[1 ;; digits]] (* Jean-François Alcover, Jun 21 2022, after Vaclav Kotesovec *)
  • PARI
    default(realprecision, 200); s=0; for(k=1, 500, s = s + moebius(k)/(2*k^4) * intnum(x=k,[[1], 1], (x-k)^2 * log(zeta(x))); print(s));

Extensions

Last digit corrected by Jean-François Alcover and confirmed by Vaclav Kotesovec, Jun 22 2022

A354887 Decimal expansion of Sum_{primes p} log(log(p)) / (p*log(p)).

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Jun 10 2022

Keywords

Examples

			0.6410802156599846604833518891513999518913451...
		

Crossrefs

A363368 Decimal expansion of Sum_{primes p} 1/(p*log(p)*log(log(p))).

Original entry on oeis.org

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

Views

Author

Artur Jasinski, Jun 11 2023

Keywords

Comments

Value computed and communicated by Bill Allombert and confirmed by Pascal Sebah.

Examples

			1.9069738480349544...
		

Crossrefs

Programs

  • PARI
    /* author Bill Allombert */
    \p150
    pz(x, ex=0)=
    {
    my(s=bitprecision(x));
    my(B=s/real(polcoef(x, 0))+ex);
    sum(n=1, B, my(a=moebius(n)); if(a!=0, a*log(zeta(n*x))/n));
    }
    my(P=primes([2, 61])); intnum(x=1, [oo, log(67)], (pz(x)-vecsum([p^-x|p<-P]))*intnum(s=0, [oo, 1], (x-1)^s/gamma(1+s))) + vecsum([1/p/log(p)/log(log(p))|p<-P])

A361089 a(n) = smallest integer x such that Sum_{k = 2..x} 1/(k*log(log(k))) > n.

Original entry on oeis.org

3, 5, 8, 21, 76, 389, 2679, 23969, 269777, 3717613, 61326301, 1188642478, 26651213526, 682263659097, 19720607003199, 637490095320530, 22857266906194526, 902495758030572213, 38993221443197045348, 1833273720522384358862
Offset: 2

Views

Author

Artur Jasinski, Jun 11 2023

Keywords

Comments

Because lim_{x->oo} (Sum_{k=2..x} 1 / (k*log(log(k)))) - li(log(x)) = 2.7977647035208... (see A363078) then a(n) = round(w) where w is the solution of the equation li(log(w)) + 2.7977647035208... = n.

Examples

			a(2) = 3 because Sum_{k=2..3} 1/(k*log(log(k))) = 2.18008755... > 2 and Sum_{k=2..2} 1/(k*log(log(k))) = -1.364208386450... < 2.
a(7) = 389 because Sum_{k=2..389} 1/(k*log(log(k))) = 7.000345... > 7 and Sum_{k=2..388} 1/(k*log(log(k))) = 6.99890560988... < 7.
		

Crossrefs

Programs

  • Mathematica
    (*slow procedure*)
    lim = 2; sum = 0; aa = {}; Do[sum = sum + N[1/(k Log[Log[k]]), 100];
     If[sum >= lim, AppendTo[aa, k]; Print[{lim, sum, k}];
      lim = lim + 1], {k, 2, 269777}];aa
    (*quick procedure *)
    aa = {3}; cons = 2.79776470352080492766050456553352884330850083202326989577856315;
    Do[ww = w /. NSolve[LogIntegral[Log[w]] + cons == n, w];
     AppendTo[aa, Round[ww][[1]]], {n, 3, 21}]; aa

Formula

For n >= 3, a(n) = round(w) where w is the solution of the equation li(log(w)) + 2.7977647035208... = n.

A363078 Decimal expansion of lim_{x->oo} (Sum_{k=2..x} 1 / (k*log(log(k)))) - li(log(x)).

Original entry on oeis.org

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

Views

Author

Artur Jasinski, Jun 11 2023

Keywords

Comments

Value computed and communicated by Pascal Sebah.
For the smallest integer x such that Sum_{k = 2..x} 1/(k*log(log(k))) > n see A361089.

Examples

			2.7977647035208...
		

Crossrefs

A137250 Decimal expansion of the constant sum 1/(q*log(q)), summed over prime powers q > 1.

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Mar 09 2008

Keywords

Comments

Evaluated from Sum_{m,k >= 1} A008683(k)*I(k*m)/k^2, where I(x) = Integral_{t=x..infinity} log zeta(t) dt is Cohen's underivative.

Examples

			2.0066664528310687...
		

References

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

Crossrefs

Programs

  • PARI
    default(realprecision, 200); su = 0; for(s=1, 400, su = su + sum(k=1, 500, moebius(k)/k^2 * intnum(x=s*k,[[1], 1], log(zeta(x))))/s; print(su)); \\ Vaclav Kotesovec, Jun 12 2022

Formula

Equals Sum_{n>=2} 1/(A000961(n)*log(A000961(n))).
Equals Sum_{p primes} -log(1-1/p)/log(p). - Vaclav Kotesovec, Jun 12 2022

Extensions

8 more digits from R. J. Mathar, Dec 04 2008
More terms from Vaclav Kotesovec, Jun 12 2022

A366249 Decimal expansion of lim_{x->oo} (Sum_{primes p<=x} 1/(p*log(log(p)))) - log(log(log(x))).

Original entry on oeis.org

2, 9, 3, 8, 3, 2, 9, 0, 1
Offset: 1

Views

Author

Artur Jasinski, Oct 05 2023

Keywords

Comments

Value computed and communicated by Pascal Sebah.

Examples

			2.93832901...
		

Crossrefs

Showing 1-10 of 10 results.