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 A056143 #3 Mar 30 2012 18:51:27 %S A056143 0,1,2,3,4,5,6,7,8,9,110,111,112,113,114,115,116,117,118,119,220,221, %T A056143 222,223,224,225,226,227,228,229,330,331,332,333,334,335,336,337,338, %U A056143 339,440,441,442,443,444,445,446,447,448,449,550,551,552,553,554,555 %N A056143 Concatenate ... floor[n/100], floor[n/10], n. %Y A056143 Cf. A028440, A048321, A056142. %K A056143 base,easy,nonn %O A056143 0,3 %A A056143 _Henry Bottomley_, Jun 15 2000