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%I #7 Jul 09 2015 05:47:10
%S 4,2,7,5,9,7,7,3,6,4,4,9,1,8,5,0,9,4,1,9,9,1,6,7,1,4,9,0,1,6,0,6,7,2,
%T 9,9,2,8,1,9,1,7,9,1,5,7,3,1,0,3,5,1,1,2,2,8,9,0,2,5,4,9,7,8,9,4,2,5,
%U 1,6,7,3,2,2,9,3,9,6,2,0,4,0,8,3,4,1,9,1,2,0,5,7,9,9,8,2,3,1,0,1,2,9,6,5
%N Decimal expansion of sum_{n>=1} (PolyGamma(2, n+1)/n^3) (negated).
%H Eric Weisstein's MathWorld, <a href="http://mathworld.wolfram.com/PolygammaFunction.html">Polygamma Function</a>.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Polygamma_function">Polygamma Function</a>.
%F Equals zeta(6) - zeta(3)^2.
%e -0.427597736449185094199167149016067299281917915731035112289...
%t RealDigits[Zeta[6] - Zeta[3]^2, 10, 104] // First
%o (PARI) zeta(6) - zeta(3)^2 \\ _Michel Marcus_, Jul 09 2015
%Y Cf. A002117, A013664.
%K nonn,cons,easy
%O 0,1
%A _Jean-François Alcover_, Jul 09 2015