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 A216697 #25 Sep 27 2012 14:15:50
%S A216697 24,54,780,2352,430272,184773312
%N A216697 Numbers n such that sigma(n) mod n = 12, n is divisible by 6, but n/6 is not prime.
%C A216697 Motivated by A076496 comment: if n=6p, p>3 prime, then Mod(sigma(n),n)=12. So this sequence is included in A076496, but not in A084306.
%C A216697 Next term > 10^11. - _Donovan Johnson_, Sep 27 2012
%e A216697 sigma(24) = 60 = 2*24+12, but 24/6=4 is not prime.
%o A216697 (PARI) isOk(n) = { return ((n % 6 == 0) && (! isprime(n/6)) && (sigma(n) % n == 12));}
%Y A216697 Cf. A076496, A084306.
%K A216697 nonn
%O A216697 1,1
%A A216697 _Michel Marcus_, Sep 15 2012