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A245781
Decimal expansion of the infinite product of (j/Pi)*sin(Pi/j), for j >= 2, a constant similar to the Kepler-Bouwkamp constant.
0
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.
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
KEYWORD
nonn,cons,easy
AUTHOR
STATUS
approved