Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #11 Jan 10 2022 11:55:03
%S 1,1,2,6,20,93,534,4291,47120,739310,16641941,539386425
%N Number of unlabeled, connected graphs on n vertices that have no induced subgraph isomorphic to a gem, where a gem is a 4-path with a fifth vertex adjacent to all four of the vertices in the path.
%D A. Brandstadt and D. Kratsch, "On (P5,Gem)-free and (P5,Gem,co-Gem)-free Graphs: Structure and algorithmic applications," Manuscript 2000.
%H Qingqiong Cai, Jan Goedgebeur, and Shenwei Huang, <a href="https://arxiv.org/abs/2108.05492">Some Results on k-Critical P_5-Free Graphs</a>, arXiv:2108.05492 [math.CO], 2021.
%H F. Hüffner, <a href="https://github.com/falk-hueffner/tinygraph">tinygraph</a>, software for generating integer sequences based on graph properties, version e8699da.
%K more,nonn
%O 1,3
%A _Jim Nastos_, Jan 24 2003
%E a(10)-a(12) added using tinygraph by _Falk Hüffner_, Jan 17 2016