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 1-5 of 5 results.

A138312 Decimal expansion of Mertens's constant B_3 minus Euler's constant.

Original entry on oeis.org

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

Views

Author

Dick Boland (abstract(AT)imathination.org), Mar 13 2008, Mar 14 2008, Mar 27 2008

Keywords

Comments

Arises in the coefficients of the formula for the variance of the average order of omega(n), where omega(n) is the number of distinct prime factors of n - see MathWorld "Distinct Prime Factors" link and Hardy and Wright reference.
Conjectured to be equivalent to 'kappa' = lim_{n->oo} ((Sum_{k=1..n} mu^2(k)/phi(k)) - H_n), where mu(k) is the Mobius function, phi(k) is Euler's Totient and H_n is the n-th harmonic number.
De Koninck and Doyon proved that the asymptotic sum of the index of composition Sum_{k<=x} log(k)/log(rad(k)) = x + c*x/log(x) + O(x/(log(x))^2), where c is this constant and rad(n) in the squarefree kernel of n (A007947). - Amiram Eldar, May 02 2019

Examples

			0.755366610831688021159316685988625317796300153102499062981363664872472...
		

References

  • Hardy, G. H. and Wright, E. M., "The Number of Prime Factors of n" and "The Normal Order of omega(n) and Omega(n)." Sections 22.10 and 22.11 in An Introduction to the Theory of Numbers, 5th ed. Oxford, England: Clarendon Press, pp. 354-358, 1979.

Crossrefs

Cf. A083343 (Mertens' B_3), A001620 (Euler's Constant), A138313 (The constant 'Kappa' conjectured to be equivalent to this sequence), A138316, A138317, A007947.

Programs

  • Mathematica
    f[n_] := f[n] = Sum[MoebiusMu[j]* Zeta'[j]/Zeta[j], {j, 2, n}] // RealDigits[#, 10, 105]& // First; f[100]; f[n = 200]; While[f[n] != f[n - 100], n = n + 100]; f[n] (* Jean-François Alcover, Feb 14 2013, from 2nd formula *)

Formula

Sum_{i>=1} log p_i/(p_i(p_i-1)), where p_i is the i-th prime.
Sum_{j>=2} mu(j)zeta'(j)/zeta(j), mu(j) is the Mobius function, zeta'(j) is the derivative of zeta(j).

Extensions

More terms from Jean-François Alcover, Feb 14 2013

A138316 Numerators of the squarefree totient analogs of the harmonic numbers F_n.

Original entry on oeis.org

1, 2, 5, 5, 11, 13, 41, 41, 41, 11, 113, 113, 77, 241, 497, 497, 1009, 1009, 3067, 3067, 3127, 3199, 35549, 35549, 35549, 36209, 36209, 36209, 255443, 262373, 264221, 264221, 266993, 135229, 17048, 17048, 22859, 69347, 139849, 139849, 70271, 35713
Offset: 1

Views

Author

Dick Boland (abstract(AT)imathination.org), Mar 13 2008, Mar 27 2008

Keywords

Comments

F_n-H_n approaches a constant, 'kappa', conjectured to be equivalent to the difference of B_3-gamma, where B_3 is Mertens' 3rd constant and gamma is Euler's constant.

Examples

			Numerators of F_n, e.g., F_1 = (1/1), F_2 = (1/1 + 1/1), ... F_11 = (1/1 + 1/1 + 1/2 + 0 + 1/4 + 1/2 + 1/6 + 0 + 0 + 1/4 + 1/10).
		

Crossrefs

Programs

  • Mathematica
    Table[Numerator[Sum[MoebiusMu[k]^2/EulerPhi[k], {k, 1, n}]], {n, 1, 60}]
  • PARI
    a(n) = numerator(sum(k=1, n, if (issquarefree(k), 1/eulerphi(k)))); \\ Michel Marcus, Aug 28 2018

Formula

a(n) = numerator[sum(k=1 to n)mu^2(k)/phi(k)] where mu(k) is the Mobius function and phi(k) is Euler's Totient function.

A138317 Denominators of the squarefree totient analogs of the harmonic numbers F_n.

Original entry on oeis.org

1, 1, 2, 2, 4, 4, 12, 12, 12, 3, 30, 30, 20, 60, 120, 120, 240, 240, 720, 720, 720, 720, 7920, 7920, 7920, 7920, 7920, 7920, 55440, 55440, 55440, 55440, 55440, 27720, 3465, 3465, 4620, 13860, 27720, 27720, 13860, 6930, 3465, 3465, 3465, 6930, 79695, 79695
Offset: 1

Views

Author

Dick Boland (abstract(AT)imathination.org), Mar 13 2008, Mar 27 2008

Keywords

Comments

F_n-H_n approaches a constant, 'kappa', conjectured to be equivalent to the difference of B_3-gamma, where B_3 is Mertens' 3rd constant and gamma is Euler's constant.

Examples

			Denominators of F_n, e.g., - F_1 = (1/1), F_2 = (1/1 + 1/1), ... F_11 = (1/1 + 1/1 + 1/2 + 0 + 1/4 + 1/2 + 1/6 + 0 + 0 + 1/4 + 1/10).
		

Crossrefs

Programs

  • Mathematica
    Table[Denominator[Sum[MoebiusMu[k]^2/EulerPhi[k], {k, 1, n}]], {n, 1, 60}]
  • PARI
    a(n) = denominator(sum(k=1, n, if (issquarefree(k), 1/eulerphi(k)))); \\ Michel Marcus, Aug 28 2018

Formula

a(n)=Denominator[sum(k=1 to n)mu^2(k)/phi(k)] where mu(k) is the Mobius function and phi(k) is Euler's Totient function.

A138320 Numerators of the difference between the squarefree totient analogs of the harmonic numbers and the harmonic numbers: F_n-H_n.

Original entry on oeis.org

0, 1, 2, 5, 7, 4, 173, 587, 1481, 1859, 20701, 18391, 241393, 275713, 148367, 548423, 2342059, 241321, 41436061, 19263077, 40604659, 43779103, 1009564739, 1907583043, 9002492327, 9603126977, 27322095131, 25887926681, 752184042199
Offset: 1

Views

Author

Dick Boland (abstract(AT)imathination.org), Mar 14 2008, Mar 27 2008

Keywords

Comments

F_n-H_n approaches a constant, 'kappa', conjectured to be equivalent to the difference of B_3-gamma, where B_3 is Mertens' 3rd constant and gamma is Euler's constant.

Examples

			Numerators of F_n - H_n, e.g. - F_1 - H_1 = (1/1-1/1), F_2 = ((1/1-1/1) + (1/1-1/2)),...
F_11 = ((1/1-1/1) +(1/1-1/2) +(1/2-1/3) +(0-1/4) +(1/4-1/5) +(1/2-1/6) +(1/6-1/7) +(0-1/8) +(0-1/9) +(1/4-1/10) +(1/10-1/11)).
		

Crossrefs

Programs

  • Mathematica
    Table[Numerator[Sum[MoebiusMu[k]^2/EulerPhi[k], {k, 1, n}]-HarmonicNumber[n]], {n, 1, 60}]
  • PARI
    for(n=1,60, print1(numerator(sum(k=1,n, moebius(k)^2/eulerphi(k)) - sum(j=1,n,1/j)), ", ")) \\ G. C. Greubel, Aug 31 2018

Formula

a(n) = Numerator[(Sum_{k=1..n} mu^2(k)/phi(k)) - H_n] where mu(k) is the Mobius function, phi(k) is Euler's Totient function and H_n is the n-th Harmonic Number.

A138321 Denominators of the difference between the squarefree totient analogs of the harmonic numbers and the harmonic numbers: F_n - H_n.

Original entry on oeis.org

1, 2, 3, 12, 15, 5, 210, 840, 2520, 2520, 27720, 27720, 360360, 360360, 180180, 720720, 3063060, 340340, 58198140, 29099070, 58198140, 58198140, 1338557220, 2677114440, 13385572200, 13385572200, 40156716600, 40156716600, 1164544781400, 582272390700, 18050444111700, 144403552893600
Offset: 1

Views

Author

Dick Boland (abstract(AT)imathination.org), Mar 14 2008, Mar 27 2008

Keywords

Comments

F_n - H_n approaches a constant, 'kappa', conjectured to be equivalent to the difference of B_3-gamma, where B_3 is Mertens's 3rd constant and gamma is Euler's constant.
Original data was given as {1, 1, 12, 24, 240, 80, 560, 3360, 30240, 7560, 831600, 831600, 93600, 21621600, 6177600, 12355200, 2940537600, 980179200, 55870214400, 2234808576, 3724680960, 177365760, 49597067520, 29758240512, 3719780064000} which is in error for this sequence. - G. C. Greubel, Sep 14 2018

Examples

			Denominators of F_n - H_n, e.g., -F_1 - H_1 = (1/1 - 1/1), F_2 = ((1/1 - 1/1) + (1/1 - 1/2)), ...
F_11 = ((1/1 - 1/1) + (1/1 - 1/2) + (1/2 - 1/3) + (0 - 1/4) + (1/4 - 1/5) + (1/2 - 1/6) + (1/6 - 1/7) + (0 - 1/8) + (0 - 1/9) + (1/4 - 1/10) + (1/10 - 1/11)).
		

Crossrefs

Programs

  • Mathematica
    Table[Denominator[Sum[MoebiusMu[k]^2/EulerPhi[k], {k, 1, n}]-HarmonicNumber[n]], {n, 1, 60}]
  • PARI
    for(n=1, 60,print1(denominator(sum(k=1,n, moebius(k)^2/eulerphi(k) ) - sum(j=1, n, 1/j)), ", ")) \\ G. C. Greubel, Sep 14 2018

Formula

a(n) = denominator( (Sum_{k=1..n} mu(k)^2/phi(k)) - H_n) where mu(k) is the Mobius function, phi(k) is Euler's Totient function and H_n is the n-th Harmonic Number.

Extensions

Data replaced by G. C. Greubel, Sep 14 2018
Showing 1-5 of 5 results.