A006389 Number of unsensed planar maps with n edges and without faces of degree 1.

1, 1, 2, 6, 18, 68, 313, 1592, 9187, 57451, 384450, 2703970, 19769311

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• more

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Timothy R. Walsh, Generating nonisomorphic maps without storing them, SIAM J. Algebraic Discrete Methods 4 (1983), no. 2, 161-178.

Crossrefs

Cf. A006385, A006388 (sensed), A379433 (rooted).

Extensions

a(8)-a(12) from Sean A. Irvine, Mar 28 2017

a(0)=1 prepended by Andrew Howroyd, Jan 16 2025