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 A159900 #3 Mar 30 2012 19:00:15 %S A159900 1,12,123,1235,12357,1235711,123571113,12357111317,1235711131719, %T A159900 123571113171923,12357111317192329,1235711131719232931, %U A159900 123571113171923293137,12357111317192329313741 %N A159900 Concatenation of the first n elements of A008578. %F A159900 Prepend 1 to the terms of A019518(n) - _R. J. Mathar_, Apr 28 2009. %Y A159900 Cf. A158611. %K A159900 nonn,base,less %O A159900 1,2 %A A159900 _Jaroslav Krizek_, Apr 25 2009 %E A159900 Slightly edited by _R. J. Mathar_, Apr 28 2009 %E A159900 Correction for change of offset in A158611 and A008578 in Aug 2009 _Jaroslav Krizek_, Jan 27 2010