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 A329788 #21 Dec 02 2019 03:13:08
%S A329788 1,2,6,24,116,672,4520,35050,303468,2934652,31145346,361323708,
%T A329788 4535359000,61431851046,890284097146,13784350300996
%N A329788 Total number of graceful labelings of connected graphs with n edges.
%C A329788 In general, consider a connected graph with E edges and V vertices. The vertices are given labels in the range 0 to E so that the differences between edges' endpoints are {1,...,E}. None of the vertices are isolated; hence each vertex label participates in at least one edge. For this sequence V is unrestricted and E = n.
%H A329788 D. E. Knuth, <a href="https://cs.stanford.edu/~knuth/programs/graceful-count.w">Program for counting graceful graph labelings.</a>
%Y A329788 Cf. A033472 (V=E+1), A329789 (V=E). A diagonal of the triangle in A329790.
%K A329788 nonn,more
%O A329788 1,2
%A A329788 _N. J. A. Sloane_, Dec 01 2019, based on email from _Don Knuth_, Dec 01 2019