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%I #12 Mar 09 2018 06:27:42
%S 0,2,9,4,15,3,14,4,15,5,22,5,26,7,21,6,34,9,38,7,21,11,46,4,30,13,24,
%T 9,58,14,62
%N Number of vertices of minimal graph with an automorphism group of order n.
%C Most terms were found in the thread "Automorphismengruppen von Graphen" in the German newsgroup "de.sci.mathematik" (mostly by Hauke Klein). The terms a(9)=15, a(15)=21, a(21)=23, a(27)=24, a(30)=14 still need verification.
%C The value A080803(21) = 21 is due to Gordon Royle, who found a graph with 21 vertices whose automorphism group is non-Abelian of order 21 (a 2'-Hall subgroup of the group PSL_2(7)).
%H Jeremy Tan, <a href="https://math.stackexchange.com/questions/2681439/gordon-royles-21-vertex-21-automorphism-graph">Gordon Royle's 21-vertex 21-automorphism graph</a>, Math StackExchange, March 2018.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/AutomorphismGroup.html">Automorphism Group</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphAutomorphism.html">Graph Automorphism</a>
%e a(4)=4 because the graph with 4 vertices and exactly one edge has an automorphism group of order 4 and no smaller graph has exactly 4 automorphisms.
%Y Cf. A058890.
%K more,nice,nonn
%O 1,2
%A _Jens Voß_, Mar 26 2003
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