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.
%I A230164 #17 Jul 28 2024 17:02:42 %S A230164 17296,24016,334144656,358585488,2955423888,311063879024 %N A230164 Numbers k such that k' = sigma(k), where k' is the arithmetic derivative of k. %C A230164 a(7) > 10^12. - _Giovanni Resta_, Mar 11 2014 %e A230164 If k = 17296 then k' = sigma(k) = 35712. If k = 24016 then k' = sigma(k) = 49600. %p A230164 with(numtheory); P:= proc(q) local a,n,p; %p A230164 for n from 1 to q do a:=n*add(op(2,p)/op(1,p),p=ifactors(n)[2]); %p A230164 if sigma(n)=a then print(n); fi; od; end: P(10^9); %Y A230164 Cf. A003415, A229342, A230165, A342021. %K A230164 nonn,more %O A230164 1,1 %A A230164 _Paolo P. Lava_, Oct 14 2013 %E A230164 a(3)-a(5) from _Giovanni Resta_, Oct 14 2013 %E A230164 a(6) from _Giovanni Resta_, Mar 11 2014