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 A144123 #4 Mar 30 2012 18:52:27 %S A144123 4,6,8,9,1000000000000,14,240,18,2097152000000000000000000000, %T A144123 165251092644282265779977014214656,650,27, %U A144123 831554883865300668552224606420411230629920768,33,1190,1368 %N A144123 (0, 1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13,..) becomes (4, 6, 8, 9, 10^12, 14, 15*16, 18, 20^21, 22^24, 25*26, 27, 28^30*32, 33, ..). %e A144123 10^12=1000000000000=a(5). %e A144123 14=a(6). %e A144123 15*16=240=a(7). %e A144123 20^21=2097152000000000000000000000, %e A144123 etc. %Y A144123 Cf. A002808, A136740, A136811, A143716. %K A144123 nonn %O A144123 1,1 %A A144123 _Juri-Stepan Gerasimov_, Nov 17 2008 %E A144123 Corrected (18 inserted) and extended by _R. J. Mathar_, Apr 28 2010