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 A078279 #2 Dec 05 2013 19:55:57 %S A078279 44,4664,486684,49688694,416089981604,4162819019081624, %T A078279 41648192110019281644,416581941102112019481654, %U A078279 4166819511041122114019581664,41688196110511241142115019681684 %N A078279 a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of first n composite numbers, while if even-positioned digits are deleted then one gets reverse concatenation of first n composite numbers. Position of least significant digit is considered to be 1. %e A078279 a(4) = 49688694: deleting alternate digits starting from the LSD leaves 4689. Deleting the other ones leaves 9864. %Y A078279 Cf. A078278, A078280, A078281. %K A078279 base,nonn %O A078279 1,1 %A A078279 _Amarnath Murthy_, Nov 25 2002 %E A078279 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003