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%I #5 Mar 31 2012 13:22:06
%S 1,1,1,2,1,1,8,21,5,4,4,4,32,4,16,7,9,1,14,5,32,22,35,6,21,11,22,3,72,
%T 48,20,1,8,1,36,30,32,6,26,14,2,22,32,6,48,37,2,58,1,74
%N Least a(n) such that p(n)#*(p(n)#+a(n))-1 is prime with p(i)#=i-th primorial.
%C As n increases sum(a(i)) for i=1 to n tends to e^gamma/2*n*(n+1)/2, notice that n*(n+1)/2 is triangular number. [From _Pierre CAMI_, Oct 16 2008]
%H Pierre CAMI, <a href="/A144946/b144946.txt">Table of n, a(n) for n = 1..500</a>
%e 2*(2+1)-1=5 prime so a(1)=1 6*(6+1)-1=41 prime so a(2)=1 30*(31)-1=929 prime so a(3)=1.
%Y Cf. A144947
%K nonn
%O 1,4
%A _Pierre CAMI_, Sep 26 2008, Oct 16 2008
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