A330346 Number of unlabeled simple graphs covering n vertices with exactly two automorphisms.

0, 0, 1, 1, 2, 9, 37

Offset

0,5

Comments

First differs from A241454 at n = 8.

Links

Table of n, a(n) for n=0..6.

Gus Wiseman, The a(5) = 9 graphs with exactly two automorphisms.

Example

Non-isomorphic representatives of the a(5) = 9 graphs:
  {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 A330297.

The non-covering version is A330344.

Unlabeled covering graphs are A002494.

Unlabeled connected graphs with exactly two automorphisms are A241454.

Graphs with exactly two automorphisms are A330297 (labeled covering), A330344 (unlabeled), A330345 (labeled), A330346 (unlabeled covering), A241454 (unlabeled connected).

Cf. A000088, A003400, A055621, A124059, A330098, A330227, A330230, A330231, A330294, A330295, A330343.

Sequence in context: A101610 A111601 A328268 * A280351 A306721 A306852

Adjacent sequences: A330343 A330344 A330345 * A330347 A330348 A330349

Keyword

nonn,more

Author

Gus Wiseman, Dec 12 2019

Status

approved