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 A057858 #4 Jul 15 2016 14:27:53 %S A057858 0,0,2,19,158,1825,24264,418343,8040802,186597501,5447823140, %T A057858 169904387719,6317118448398,260105476071197 %N A057858 Number of residue classes modulo n-th primorial number which contain only composite numbers. %F A057858 a(n) = A002110(n) - A057857(n). %e A057858 a(3) = 19 since 30 is the 3rd primorial number and 30k+m is always composite if m = 0, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27 or 28. %Y A057858 Cf. A002110, A057857. %K A057858 nonn %O A057858 0,3 %A A057858 _Henry Bottomley_, Sep 08 2000