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 A165740 #17 May 27 2014 00:15:24 %S A165740 3,5,6,9,10,12,15,17,18,20,21,24,25,27,30,31,33,34,35,36,39,40,42,45, %T A165740 48,50,51,54,55,57,60,62,63,65,66,68,69,70,72,75,78,80,81,84,85,87,90, %U A165740 93,95,96,99,100,102,105,108,110,111,114,115,117,119,120,123,124,125,126 %N A165740 Positive integers n such that solution to the toric n X n "Lights Out" puzzle is not unique (up to the order of flippings; each flipping appears at most once). %C A165740 Complement to the sequence A165741 in the set of positive integers. %C A165740 Any positive multiple of a member of this sequence is also a member. Primitive elements are in A007802. - _Thomas Buchholz_, May 23 2014 %D A165740 See A165738 for the references. %H A165740 Max Alekseyev and Thomas Buchholz, <a href="/A165740/b165740.txt">Table of n, a(n) for n = 1..1000</a> [terms 67 through 1000 were computed by Thomas Buchholz, May 20 2014] %F A165740 A number n is in this sequence iff A165738(n) > 0. %Y A165740 Cf. A159257, A075462, A117870, A165741, A007802, A165738. %K A165740 nonn %O A165740 1,1 %A A165740 _Max Alekseyev_, Sep 25 2009 %E A165740 More terms from _Thomas Buchholz_, May 20 2014