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 A069631 #3 Dec 05 2013 19:55:16 %S A069631 4,41,241,2411,32411,324113,6324113,63241133,1563241133,15632411339, %T A069631 815632411339,81563241133909,1981563241133909,198156324113390947, %U A069631 24198156324113390947,2419815632411339094781,212419815632411339094781 %N A069631 a(1) = 4; a(2n) = smallest prime starting (most significant digits) with a(2n-1). a(2n+1) = smallest prime ending (least significant digits)in a(2n). %Y A069631 Cf. A069614 to A069621, A069628 to A069636. %K A069631 nonn,base %O A069631 1,1 %A A069631 _Amarnath Murthy_, Mar 27 2002 %E A069631 Edited and extended by _Robert G. Wilson v_, Apr 03 2002