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 A237286 #18 Mar 12 2014 17:16:00 %S A237286 6,25,28,496,652,8128,10682,10828,33550336,44655764,8589869056, %T A237286 8623554304,137438691328 %N A237286 Numbers n such that sigma(n) - n = perfect number (A000396). %C A237286 Also numbers n such that sum of the proper divisors of n (A001065) = perfect number (A000396). %C A237286 Supersequence of perfect numbers (A000396). %C A237286 a(14) > 10^12. - _Giovanni Resta_, Mar 01 2014 %C A237286 Up to a(13), note that the terms that are not perfect are deficient. - _Michel Marcus_, Mar 12 2014 %e A237286 Number 25 is a term because sigma(25) - 25 = 31 - 25 = 6 (perfect number). %o A237286 (PARI) isok(n) = sigma(smn=sigma(n) - n) == 2*smn; \\ _Michel Marcus_, Mar 01 2014 %Y A237286 Cf. A000203 (sigma(n)). %K A237286 nonn,more %O A237286 1,1 %A A237286 _Jaroslav Krizek_, Feb 28 2014 %E A237286 a(10) from _Michel Marcus_, Mar 01 2014 %E A237286 a(11)-a(13) from _Giovanni Resta_, Mar 01 2014