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 A213220 #10 Mar 02 2013 22:04:22 %S A213220 1,7,9,15,23,26,31,34,41,47,52,57,63,68,76,82,88,95,100,106,110,118, %T A213220 124,133,139,145,152,159,167,174,184,191,197,204,209,218,224,236,243, %U A213220 252,261,270,276,284,291,299,307,319,326,334,340,348,355,363,370,377,384,391,397,405,415,423,431,440,447,454,462,472 %N A213220 Positions in A114183 where doubling runs begin. %H A213220 N. J. A. Sloane, <a href="/A213220/b213220.txt">Table of n, a(n) for n = 1..7328</a> %Y A213220 Cf. A114183, A221715, A221716 (first differences). %K A213220 nonn %O A213220 1,2 %A A213220 _N. J. A. Sloane_, Mar 02 2013