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 A157223 #12 May 09 2018 23:01:44 %S A157223 0,1,1,2,2,5,3,4,5,8,5,10,6,11,10,10,8,17,9,16,14,17,11,20,14,20,17, %T A157223 22,14,34,15,22,22,26,22,34,18,29,26,32,20,46,21,34,34,35,23,44,27,44, %U A157223 34,40,26,53,34,44,38,44,29,68,30,47,46,46,40,70,33,52,46 %N A157223 Number of primitive inequivalent oblique sublattices of centered rectangular lattice of index n. %H A157223 John S. Rutherford, <a href="http://dx.doi.org/10.1107/S010876730804333X">Sublattice enumeration. IV. Equivalence classes of plane sublattices by parent Patterson symmetry and colour lattice group type</a>, Acta Cryst. (2009). A65, 156-163. [See Table 4.] %F A157223 a(n) = (A001615(n) - A060594(n))/2. - _Andrey Zabolotskiy_, May 09 2018 %Y A157223 Cf. A060594 (primitive mirror-symmetric sublattices), A145390 (all mirror-symmetric sublattices), A145391 (all sublattices), A001615, A304182. %K A157223 nonn %O A157223 1,4 %A A157223 _N. J. A. Sloane_, Feb 25 2009 %E A157223 New name and more terms from _Andrey Zabolotskiy_, May 09 2018