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%I #3 Mar 31 2012 12:38:27
%S 4,12,18,72,192,270,1488,1872,1482,1872,1152,2268,6552,3672,6552,
%T 10890,3528,5280,7560,7488,13680,23040,17388,29760,21600,23040,65520,
%U 87120,51480,34848,65268,127680,122400,134400,114660,137088,206640,134400
%N Twin prime averages which are also the sum of the divisors of a triangular number.
%e The triangular number A000217(3)= 6 has a sum of divisors 1+2+3+6 = 12 = A014574(3) which is also the average of the twin primes 11 and 13.
%t t[n_]:=n*(n+1)/2; f[n_]:=Plus@@Divisors[t[n]]; lst={};Do[p=f[n];If[PrimeQ[p-1]&&PrimeQ[p+1], AppendTo[lst,p]],{n,7!}];lst
%Y Cf. A074285, A014574 [R. J. Mathar, Oct 14 2008]
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Oct 08 2009
%E Definition and example rewritten by _R. J. Mathar_, Oct 14 2009