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.

A345327 Decimal expansion of a constant Y2 related to the asymptotics of A000203.

Original entry on oeis.org

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

Views

Author

Vaclav Kotesovec, Jun 14 2021

Keywords

Examples

			0.5073388825830843781004978765159526773890196348281644808049...
		

Crossrefs

Programs

  • Mathematica
    $MaxExtraPrecision = 1000; Do[ratfun = (p - 1)^2 * Sum[j/(p^j - 1)/(p^(j + 1) - 1), {j, 1, m}]/(p*(1 - (p - 1)^2/p * Sum[1/(p^j - 1)/(p^(j + 1) - 1), {j, 1, m}])); zetas = 0; ratab = Table[konfun = Together[ratfun + c/(p^power - 1)]; coefs = CoefficientList[Numerator[konfun], p]; sol = Solve[Last[coefs] == 0, c][[1]]; zetas = zetas + c*Zeta'[power]/Zeta[power] /. sol; ratfun = konfun /. sol, {power, 2, 40}]; Print[N[Sum[Log[p]*ratfun /. p -> Prime[k], {k, 1, m}] + zetas, 110]], {m, 10, 250, 10}]

Formula

Equals Sum_{p primes} (p-1)^2 * g(p) * log(p) / (p*f(p)), where f(p) = 1 - (p-1)^2/p * Sum_{j>=1} 1/((p^j - 1)*(p^(j+1) - 1)) and g(p) = Sum_{j>=1} j/((p^j - 1)*(p^(j+1) - 1)).
Sum_{k=1..n} 1/A000203(k) ~ Y1*log(n) + Y1*(gamma + Y2), where gamma = A001620, Y1 = A308039, Y2 = A345327.