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 A104760 #2 Oct 02 2013 15:47:26 %S A104760 57,77,3777,17777,277777,1777777,17777777,707777777,3777777777, %T A104760 17777777777,577777777777,1777777777777,37777777777777, %U A104760 757777777777777,4777777777777777,37777777777777777,277777777777777777 %N A104760 Smallest semiprime containing exactly n 7's. %e A104760 a(2)=77 because 77 is the smallest semiprime containing exactly two 7's. %K A104760 base,nonn %O A104760 1,1 %A A104760 _Shyam Sunder Gupta_, Apr 24 2005