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 A234238 #19 Feb 08 2016 10:14:26 %S A234238 24,54,121,304,780,2352,127744,430272,33501184,184773312,8589082624 %N A234238 Sporadic solutions to sigma(n) == 12 modulo n. %C A234238 Terms of A076496 that are either not divisible by 6 or such that x/6 is not coprime to 6. %C A234238 10384593717069654320312270165377024 is also a term. - _Donovan Johnson_, Dec 23 2013 %H A234238 A. Anavi, P. Pollack, C. Pomerance, <a href="http://dx.doi.org/10.1142/S1793042112501266">On congruences of the form sigma(n) == a (mod n)</a>, Int. J. Number Theory 09, 115 (2013). %H A234238 P. Pollack, <a href="http://alpha.math.uga.edu/~pollack/CNTA2012.pdf">The sum of divisors of n, modulo n</a>, CNTA 2012. %e A234238 sigma(24) % 24 = 12, and 24/6 is not coprime to 6, hence 24 is here. %e A234238 sigma(121) % 121 = 12, and 121 is not divisible by 6, hence 121 is here. %o A234238 (PARI) a(n) = m = 6; a = sigma(m) ; ((sigma(n) % n) == a) && ((n % m) || (!(n % m) && (gcd(m, (n/m)) != 1))); %Y A234238 Cf. A076496. %Y A234238 Supersequence of A084306. %K A234238 nonn,more %O A234238 1,1 %A A234238 _Michel Marcus_, Dec 21 2013 %E A234238 a(11) from _Donovan Johnson_, Dec 23 2013