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 A117326 #3 Mar 30 2012 18:40:36 %S A117326 13,17,18,20,21,27,28,30,32,41,42,43,46,47,49,53,55,56,58,59,63,69,72, %T A117326 75,81 %N A117326 Indices of semiprimes in A117322 prime(n) modulo semiprime(n). %e A117326 a(1) = 13 because A117322(13) = prime(13) modulo semiprime(13) = 41 mod 35 = 6 = 2 * 3 is semiprime. %e A117326 a(2) = 17 because A117322(17) = 59 mod 49 = 10 = 2 * 5 is semiprime. %e A117326 a(3) = 18 because A117322(18) = 61 mod 51 = 10 = 2 * 5 is semiprime. %e A117326 a(4) = 20 because A117322(20) = 71 mod 57 = 14 = 2 * 7 is semiprime. %K A117326 easy,nonn %O A117326 1,1 %A A117326 _Jonathan Vos Post_, Mar 08 2006