A006407 Number of unsensed 2-connected planar maps with n edges. (Formerly M1157)

1, 1, 2, 4, 8, 20, 58, 177, 630, 2410, 9772, 41423, 181586, 814412, 3722445

Offset

3,3

Comments

Equivalently, a(n) is the number of embeddings on the sphere of 2-connected planar graphs with n edges. - Andrew Howroyd, Mar 27 2021

References

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

Links

Table of n, a(n) for n=3..17.

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

Formula

a(n) = Sum_{k=3..n} A342060(k, n+2-k). - Andrew Howroyd, Mar 27 2021

Crossrefs

Cf. A006403, A006405, A006406 (sensed case), A342060.

Sequence in context: A000116 A302862 A344490 * A100447 A241891 A112278

Adjacent sequences: A006404 A006405 A006406 * A006408 A006409 A006410

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

a(11) and a(12) from Sean A. Irvine, Apr 03 2017

a(13)-a(17) from Andrew Howroyd, Mar 27 2021

Status

approved