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 A138975 #3 Mar 31 2012 10:26:07 %S A138975 23,43,223,233,433,2333,3323,3343,3433,23333,32233,32323,33223,33343, %T A138975 232333,233323,323233,323333,333233,333323,333433,334333,343333, %U A138975 2332333,2333323,3223333,3233323,3233333,3332233,3333233,3333433,3433333 %N A138975 Primes made up of only 3's and a 4 and at most two 2's. %Y A138975 Cf. A020458, A138974. %K A138975 nonn,base %O A138975 1,1 %A A138975 _Lekraj Beedassy_, Apr 05 2008