A245781 Decimal expansion of the infinite product of (j/Pi)*sin(Pi/j), for j >= 2, a constant similar to the Kepler-Bouwkamp constant.

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

Offset

0,1

References

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 6.3 Kepler-Bouwkamp constant, p. 428.

Links

Table of n, a(n) for n=0..101.

Formula

exp( -sum_{k >= 1} zeta(2*k)*(zeta(2*k)-1)/k ).

Example

0.32870969168566393036259767023839643402099763855589812883...

Mathematica

digits = 102; Exp[-NSum[Zeta[2*k]*(Zeta[2*k]-1)/k, {k, 1, Infinity}, NSumTerms -> 200, WorkingPrecision -> digits+10]] // RealDigits[#, 10, digits]& // First

Crossrefs

Cf. A085365.

Sequence in context: A132887 A364317 A092174 * A239803 A083514 A123696

Adjacent sequences: A245778 A245779 A245780 * A245782 A245783 A245784

Keyword

nonn,cons,easy

Author

Jean-François Alcover, Aug 01 2014

Status

approved