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 A102172 #13 Aug 08 2021 11:34:42 %S A102172 5,9,20,29,31,32,51,54,56,76,81,83,89,98,139,145,292,314 %N A102172 Iccanobirt semiprime indices (2 of 15): Indices of semiprime numbers in A102112. %F A102172 A102112(a(n)) = A102192(n). %Y A102172 Cf. A001358, A102112, A102171-A102185, A102192. %K A102172 nonn,more,less,base %O A102172 1,1 %A A102172 _Jonathan Vos Post_ and _Ray Chandler_, Dec 31 2004 %E A102172 Offset changed to 1 and a(17)-a(18) from _Jinyuan Wang_, Aug 08 2021