cp's OEIS Frontend

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.

A382181 Number of unlabeled graphs with n vertices (including disconnected graphs) which are squares.

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%I A382181 #13 Mar 18 2025 21:40:11
%S A382181 1,1,2,3,6,11,28,77,307,1688,14620,197050,4137271
%N A382181 Number of unlabeled graphs with n vertices (including disconnected graphs) which are squares.
%C A382181 If G is an unlabeled finite simple graph, define its square S(G) to be the graph with the same vertices as G. The edges of S(G) are the edges of G together with an edge from vertex u to v whenever u and v are not adjacent in G but are joined by a path of length 2.
%D A382181 Frank Harary and Ian C. Ross, The Square of a Tree, Bell Labs Memorandum MM-59-122-2, May 16, 1959, 11 pages.
%H A382181 A. Mukhopadhyay, <a href="https://doi.org/10.1016/S0021-9800(67)80030-9">The Square Root of a Graph</a>, J Comb. Th., 2, (1967), 290-295.
%H A382181 Ian C. Ross and Frank Harary, <a href="https://doi.org/10.1002/j.1538-7305.1960.tb03936.x">The square of a tree</a>, The Bell System Technical J, 39, 3, May 1960.
%Y A382181 Euler transform of A382180.
%K A382181 nonn,more
%O A382181 0,3
%A A382181 _Brendan McKay_ and _Sean A. Irvine_, Mar 17 2025