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 A084449 #9 Jul 29 2017 12:47:44 %S A084449 0,4,9,35,42,101,143,365,693,729,926,1691,1721,2264,2858,3671,4919, %T A084449 7851,8469,8988,11401,12087,15246,21265,21410,28542,30539,35126,40991, %U A084449 49589,51956,59259,68723,86325,89978,106190,114594,122923,143724,150610 %N A084449 Positions of sevens (ground states) in A084451. %H A084449 A. Karttunen, <a href="/A084507/a084507.scm.txt">Scheme-program for computing this sequence</a> %Y A084449 First differences: A084465. %K A084449 nonn %O A084449 0,2 %A A084449 _Antti Karttunen_, Jun 02 2003 %E A084449 More terms from _David Wasserman_, Dec 30 2004