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%I A245781 #5 Aug 01 2014 11:19:41
%S A245781 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,
%T A245781 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,
%U A245781 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
%N A245781 Decimal expansion of the infinite product of (j/Pi)*sin(Pi/j), for j >= 2, a constant similar to the Kepler-Bouwkamp constant.
%D A245781 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 6.3 Kepler-Bouwkamp constant, p. 428.
%F A245781 exp( -sum_{k >= 1} zeta(2*k)*(zeta(2*k)-1)/k ).
%e A245781 0.32870969168566393036259767023839643402099763855589812883...
%t A245781 digits = 102; Exp[-NSum[Zeta[2*k]*(Zeta[2*k]-1)/k, {k, 1, Infinity}, NSumTerms -> 200, WorkingPrecision -> digits+10]] // RealDigits[#, 10, digits]& // First
%Y A245781 Cf. A085365.
%K A245781 nonn,cons,easy
%O A245781 0,1
%A A245781 _Jean-François Alcover_, Aug 01 2014

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