A366315 Number of Harris graphs with n vertices. Harris graphs are 1-tough, Eulerian graphs that are non-Hamiltonian.
0, 0, 0, 0, 0, 0, 1, 3, 26, 340, 7297, 233608
Offset: 1
Examples
a(7)=1 because the only Harris graph of 7 vertices (0..6) has edges {(0,1), (0,2), (0,3), (0,4), (1,2), (1,3), (1,5), (2,3), (2,6), (3,4), (3,5), (3,6)}. - _Sean A. Irvine_, Oct 18 2023
Links
- Francesca Gandini, Shubhra Mishra, and Douglas Shaw, Families of Harris Graphs, arXiv:2312.10936 [math.CO], 2023.
- Shubhra Mishra, Illustration for a(7) = 1: the unique minimal Harris graph of order 7
- Shubhra Mishra, Illustration for a(8) = 3: the three order 8 Harris graphs
- Douglas J. Shaw, Harris Graphs--A Graph Theory Activity for Students and Their Instructors, The College Mathematics Journal, 49 (2018), 5, 323-326.
Crossrefs
Cf. A007031.
Extensions
a(11)-a(12) from Sean A. Irvine, Oct 18 2023
Comments