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Numbers n such that sigma(n) - n = n - pi(n) - 1 where pi(n) is A000720.
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%I #9 Mar 31 2017 18:36:53

%S 1,5,9,26,236,244,4862,5396,6868,9608,9704,23764,82665,733064,

%T 25881904,25886864,33299110,261851668

%N Numbers n such that sigma(n) - n = n - pi(n) - 1 where pi(n) is A000720.

%C a(19) > 3*10^12. - _Giovanni Resta_, Mar 31 2017

%t For[i = 1, i < 10^9, i++, If[DivisorSigma[1, i] - i == i - PrimePi[i] - 1, Print[i]]; ]; - Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 29 2006

%Y Cf. A037172.

%K more,nonn

%O 1,2

%A _Naohiro Nomoto_

%E More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 29 2006