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 A307277 #11 Dec 07 2020 08:16:55 %S A307277 1,1,2,1,1,3,4,4,3,4,3,6,3,7,6,10,7,17,6,8,13,6,13,13,14,17,10,20,18, %T A307277 10,15 %N A307277 Number of even, unimodular, positive definite lattices of dimension 4 over a real quadratic number field Q(sqrt(D)) of fundamental discriminant d = A306300(n). %H A307277 Britta Habdank-Eichelsbacher, <a href="http://sfb343.math.uni-bielefeld.de/sfb343/preprints/pre95005.ps.gz">Unimodulare Gitter über Reell-Quadratischen Zahlkörpern</a>, Ergänzungsreihe 95-005, Univ. Bielefeld, 1995. See Section 4.2. %Y A307277 Cf. A003658, A306300. %K A307277 nonn,more %O A307277 1,3 %A A307277 _N. J. A. Sloane_, Apr 03 2019