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%I #19 Oct 07 2019 13:25:30
%S 13,2,179,55439,232792559,130429015516799
%N a(n) is the smallest prime q such that floor(sigma(sigma(q))/q) = n.
%C a(7) <= 9854961523502269526351999. If a(7) + 1 is in A025487 then a(7) = 9854961523502269526351999. a(3) + 1 through a(6) + 1 are in A025487. - _David A. Corneth_, Sep 03 2019
%F a(n) >= A091439(n). - _David A. Corneth_, Sep 03 2019
%e a(4) = 55439 because floor(sigma(sigma(55439))/55439) = floor(232128/55439) = n = 4.
%e a(5) = 232792559 because floor(sigma(sigma(a(5)))/a(5)) = floor(5.02561) = 5.
%Y Cf. A000203, A051027, A008333, A025487, A091439, A098219, A098220, A098221.
%K nonn,more
%O 1,1
%A _Labos Elemer_, Oct 25 2004
%E a(6) from _Charles R Greathouse IV_, Mar 14 2011
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