%I #2 Mar 31 2012 13:20:12
%S 3,21,3003,969969,872002131,1537339756953,5532885785273847,
%T 28676947025074349001,298326279901848452657403,
%U 3479379402495258503343291189,66257821961717207679166294112127
%N Denominators of partial sums of the Brun series divided by 5.
%C Numerators divided by 4 are given by A117507.
%C See A117507 for more information.
%F a(n)=denominator(r(n))/5, with r(n):=sum(1/ltp(k) + 1/(ltp(k)+2),k=1..n), n>=1, with ltp(k):=A001359(k) (lesser twin primes).
%K nonn,easy,frac
%O 1,1
%A _Wolfdieter Lang_, Apr 13 2006