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 A054903 #21 Sep 02 2019 15:26:06 %S A054903 104,147,596,1415,4850,5337,370047,1630622,35020303,120221396, %T A054903 3954451796,742514284703 %N A054903 Composite numbers n such that sigma(n)+6 = sigma(n+6), where sigma=A000203. %C A054903 Complement of A023201 with respect to A015914. %C A054903 Intersection of A015914 and A018252. %C A054903 Below 1000000 there are only 7 such composite numbers, compared with more than 16000 primes. %C A054903 a(13) > 10^13. - _Giovanni Resta_, Jul 11 2013 %D A054903 J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 104, p. 37, Ellipses, Paris 2008. %e A054903 n=104, sigma(104)+6 = 210+6 = 216 = sigma(104+6) = sigma(110). %e A054903 a(4) = 1415 = 5*283, 1415+6 = 1421 = 7*7*29: %e A054903 sigma(1415) = 1+5+283+1415 = 1704, %e A054903 sigma(1421) = 1+7+29+49+203+1421 = 1710 = sigma(1415)+6. %o A054903 (PARI) forcomposite(n=9,1e7,if(sigma(n)+6==sigma(n+6),print1(n", "))) \\ _Charles R Greathouse IV_, Feb 14 2013 %Y A054903 Cf. A015913-A015917, A023200-A023203, A046133, A001359, A054799. %K A054903 nonn,more %O A054903 1,1 %A A054903 _Labos Elemer_, May 23 2000 %E A054903 More terms from _Jud McCranie_, May 25 2000 %E A054903 New definition from _Reinhard Zumkeller_, Jan 27 2009 %E A054903 Edited by _N. J. A. Sloane_, Jan 31 2009 at the suggestion of _R. J. Mathar_. %E A054903 a(12) from _Giovanni Resta_, Jul 11 2013