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A138312 Decimal expansion of Mertens's constant B_3 minus Euler's constant. 6
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 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

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' = limit_{n -> infty)((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

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.

LINKS

Robert G. Wilson v, Table of n, a(n) for n = 0..9999

Dick Boland, An Analog of the Harmonic Numbers Over The Squarefree Integers

David Broadhurst, The Mertens Constant

Jean-Marie De Koninck and Nicolas Doyon, À propos de l’indice de composition des nombres, Monatshefte für Mathematik, Vol. 139, No. 2 (2003), pp. 151-167, alternative link.

Anne-Maria Ernvall-Hytönen, Tapani Matala-aho, Louna Seppälä, On Mahler's transcendence measure for e, arXiv:1704.01374 [math.NT], 2017. See Theorem 6.4.

Eric Weisstein's World of Mathematics, Mertens Constant

Eric Weisstein's World of Mathematics, Distinct Prime Factors

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).

EXAMPLE

0.755366610831688021159316685988625317796300153102499062981363664872472...

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 *)

CROSSREFS

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

Sequence in context: A258042 A289003 A295219 * A138313 A152115 A098842

Adjacent sequences:  A138309 A138310 A138311 * A138313 A138314 A138315

KEYWORD

cons,nonn

AUTHOR

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

EXTENSIONS

More terms from Jean-François Alcover, Feb 14 2013

STATUS

approved

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Last modified September 22 22:24 EDT 2020. Contains 337291 sequences. (Running on oeis4.)