cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A063785 Numbers n such that sigma(n) = 2n + omega(n), where omega(n) is the number of distinct prime divisors of n.

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%I A063785 #9 May 14 2023 00:37:14
%S A063785 20,104,464,1952,4030,5830,130304,522752,1848964,8382464,134193152
%N A063785 Numbers n such that sigma(n) = 2n + omega(n), where omega(n) is the number of distinct prime divisors of n.
%C A063785 It is easily proved that if 2^m-3 is prime then 2^(m-1)*(2^m-3) is in the sequence. - _Farideh Firoozbakht_, Feb 12 2008
%o A063785 (PARI) for(n=1,10^8, if(sigma(n)==2*n+omega(n),print(n)))
%Y A063785 Cf. A045768.
%K A063785 nonn,more
%O A063785 1,1
%A A063785 _Jason Earls_, Aug 17 2001