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%I #2 Mar 30 2012 17:40:36
%S 2,3,6,11,13,17,20,33,39,45,47,52,57,58,59,61,63,64,69,81,83,85,86,89,
%T 91,98,100,103,110,115,117,123,128,133,134,135,136,141,142,143,144,
%U 145,149,150,153,154,156,158,162,164,167,173,179,181,184,185,187,189
%N n+sigma(n)+sigma(sigma(n)) is a semiprime (A001358).
%e 115 + sigma(115) + sigma(sigma(115)) = 662 = 2*331
%Y Cf. A001358.
%K nonn
%O 1,1
%A _Giovanni Resta_, Feb 13 2006
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