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 A078278 #2 Dec 05 2013 19:55:57 %S A078278 22,2332,253352,27355372,213157751312,2133517117151332, %T A078278 21375173111117351372,213951771113113117751392, %U A078278 2233517911171133117117952332,22395273111911371173119127352392 %N A078278 a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of first n prime numbers, while if even-positioned digits are deleted then one gets reverse concatenation of first n prime numbers. Position of least significant digit is considered to be 1. %e A078278 a(4) = 27355372: deleting alternate digits starting from the LSD leaves 2357. Deleting the other ones leaves 7532. %Y A078278 Cf. A078279, A078280, A078281. %K A078278 base,nonn %O A078278 1,1 %A A078278 _Amarnath Murthy_, Nov 25 2002 %E A078278 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003