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%I #6 Feb 27 2014 03:38:07
%S 5,6,7,6,7,0,3,1,9,8,4,4,5,1,9,7,2,0,8,4,0,6,9,8,2,4,2,2,9,4,2,3,2,6,
%T 7,2,5,5,8,1,1,4,8,1,3,7,3,4,6,7,3,7,8,6,3,8,3,4,2,4,9,4,7,0,5,4,8,5,
%U 8,5,1,8,7,8,5,8,7,8,4,5,9,7,3,8,2,4,3,4,1,1,9,8,1,2,1,4,3,8,3,7
%N Decimal expansion of the sum 1/p(1) + 1/(p(2)*p(3)) + 1/(p(4)*p(5)*p(6)) + ..., where p(n) is the n-th prime.
%C Absolute difference between this number and A139396 is about 0.002.
%e 0.56767031984451972084069824229423267255811481373467378638342..
%p P:=proc(n) local a,b,i,j,k; a:=0.5; k:=1; for i from 2 by 1 to n do b:=1; for j from k by 1 to k+i-1 do b:=b*1/ithprime(j+1); od; k:=j; a:=evalf(a+b,105); od; print(a); end: P(100);
%Y Cf. A139396.
%K nonn,cons,easy
%O 0,1
%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Apr 18 2008
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