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 A138712 #3 Mar 30 2012 17:33:54 %S A138712 0,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0, %T A138712 0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0, %U A138712 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 %N A138712 n-th run has length n-th positive triangular number, with digits 0 and 1 only, starting with 0. %e A138712 .n ..... Run ............................... Length %e A138712 .1 ..... 0 ................................. 1 %e A138712 .2 ..... 1,1,1 ............................. 3 %e A138712 .3 ..... 0,0,0,0,0,0........................ 6 %e A138712 .4 ..... 1,1,1,1,1,1,1,1,1,1 ............... 10 %e A138712 .5 ..... 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ..... 15 %Y A138712 Cf. A000217, A057212, A138150, A138710. %K A138712 easy,nonn %O A138712 1,1 %A A138712 _Omar E. Pol_, Mar 29 2008