# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a144669 Showing 1-1 of 1 %I A144669 #8 Feb 23 2013 14:44:58 %S A144669 9,9,8,0,1,2,8,2,6,1,7,2,9,8,2,7,8,4,1,9,0,0,3,9,8,1,4,5,0,8,9,6,8,5, %T A144669 6,5,5,3,1,4,5,2,5,3,8,6,6,4,3,8,9,8,4,3,3,4,7,6,2,9,4,0,3,4,9,5,1,1, %U A144669 7,1,7,2,8,6,1,2,5,7,0,6,6,4,6,6,2,2,7,4,4,2,6,4,4,6,0,9,0,9,8,6,6,1,1,2,2 %N A144669 Decimal expansion of product_{n=2..infinity} (n^10-1)/(n^10+1). %H A144669 J. Borwein et al., Experimentation in Mathematics, 2004, section 1.2. %H A144669 E. W. Weisstein, Infinite Product, MathWorld. %e A144669 0.99801282617298278419003981450896856553... %t A144669 f[k_] := Sin[(-1)^(k/10)*Pi]; RealDigits[Pi/(5*Sinh[Pi])*Product[f[k], {k, {2, 4, 6, 8}}]/ Product[f[k], {k, {1, 3, 7, 9}}] // Re, 10, 105] // First (* _Jean-François Alcover_, Feb 12 2013 *) %Y A144669 Cf. A090986. %K A144669 nonn,cons,easy %O A144669 0,1 %A A144669 _R. J. Mathar_, Feb 01 2009 %E A144669 More terms from _Jean-François Alcover_, Feb 12 2013 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE