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 A242953 #21 Feb 16 2025 08:33:22 %S A242953 0,0,1,3,10,58,314,3798,51609,1716267 %N A242953 Number of connected graphs on n vertices whose spectrum has fewer than n distinct eigenvalues. %C A242953 The spectrum refers to the eigenvalues of the adjacency matrix. %H A242953 Travis Hoppe and Anna Petrone, <a href="https://github.com/thoppe/Encyclopedia-of-Finite-Graphs">Encyclopedia of Finite Graphs</a> %H A242953 T. Hoppe and A. Petrone, <a href="http://arxiv.org/abs/1408.3644">Integer sequence discovery from small graphs</a>, arXiv preprint arXiv:1408.3644, 2014 %H A242953 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GraphSpectrum.html">Graph Spectrum</a> %Y A242953 Cf. A064731 (integral graphs), A242952 (distinct spectrum graphs). %K A242953 nonn,more %O A242953 1,4 %A A242953 _Travis Hoppe_ and _Anna Petrone_, May 27 2014 %E A242953 Corrected, original description as the "non-real spectrum" was incorrect, by _Travis Hoppe_, Mar 23 2015