A330344 Number of unlabeled graphs with n vertices whose covered portion has exactly two automorphisms.

0, 1, 2, 4, 13, 50, 367

Offset: 1

Author

Gus Wiseman, Dec 12 2019

Keywords

• nonn
• more

Examples

			Non-isomorphic representatives of the a(2) = 1 through a(5) = 13 graphs:
  {12}  {12}     {12}           {12}
        {12,13}  {12,13}        {12,13}
                 {12,13,24}     {12,13,24}
                 {12,13,14,23}  {12,13,14,23}
                                {12,13,14,25}
                                {12,13,24,35}
                                {12,13,14,23,25}
                                {12,13,14,23,45}
                                {12,13,15,24,34}
                                {12,13,14,15,23,24}
                                {12,13,14,23,24,35}
                                {12,13,14,23,25,45}
                                {12,13,14,15,23,24,35}
		

Crossrefs

The labeled version is A330345.

The covering case is A330346 (not A241454).

Unlabeled graphs are A000088.

Unlabeled graphs with exactly one automorphism are A003400.

Unlabeled connected graphs with exactly one automorphism are A124059.

Graphs with exactly two automorphisms are A330297 (labeled covering), A330344 (unlabeled), A330345 (labeled), and A330346 (unlabeled covering).

Cf. A000612, A004111, A055621, A241454, A283877, A330098, A330227, A330230, A330231, A330233, A330294, A330295.

Formula

Partial sums of A330346.