A243372 - OEIS

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A243372

Decimal expansion of 3/(8*K), a constant related to the asymptotic evaluation of the number of positive integers that can be expressed as the sum of two coprime squares, where K is the Landau-Ramanujan constant.

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

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OFFSET

0,1

REFERENCES

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.3 Landau-Ramanujan constant, p. 100.

LINKS

Table of n, a(n) for n=0..103.

Eric Weisstein's MathWorld, Ramanujan constant

FORMULA

3/(8*K), where K is the Landau-Ramanujan constant.

EXAMPLE

0.490694050411539573600349303542589...

MATHEMATICA

digits = 104; LandauRamanujanK = 1/Sqrt[2]*NProduct[((1 - 2^(-2^n))*Zeta[2^n]/DirichletBeta[2^n])^(1/2^(n + 1)), {n, 1, 24}, WorkingPrecision -> digits + 5]; 3/(8*LandauRamanujanK) // RealDigits[#, 10, digits] & // First (* updated Mar 14 2018 *)

CROSSREFS

Cf. A064533.

Sequence in context: A097906 A373204 A070016 * A020802 A085675 A254133

Adjacent sequences: A243369 A243370 A243371 * A243373 A243374 A243375

KEYWORD

nonn,cons

AUTHOR

Jean-François Alcover, Jun 04 2014

STATUS

approved