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 A067504 #10 Aug 15 2017 03:15:02 %S A067504 1,7,2401,1977326743 %N A067504 Powers of 7 with digit sum also a power of 7. %C A067504 Next terms are 7^4433, 7^30810. - _Sascha Kurz_, Mar 18 2002 %Y A067504 Cf. A067499, A067500, A067501, A067502, A067503. %Y A067504 Subsequence of A000420. %K A067504 base,easy,nonn %O A067504 1,2 %A A067504 _Amarnath Murthy_, Feb 11 2002