cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A006407 Number of unsensed 2-connected simple planar maps with n edges.

Original entry on oeis.org

1, 1, 2, 4, 8, 20, 58, 177, 630, 2410, 9772, 41423, 181586, 814412, 3722445
Offset: 3

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Author

N. J. A. Sloane

Keywords

Comments

A simple planar map is a planar map without loops or parallel edges.
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

Crossrefs

Cf. A006403, A006405, A006406 (sensed case), A342060, A379437 (rooted).

Formula

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

Extensions

a(11) and a(12) from Sean A. Irvine, Apr 03 2017
a(13)-a(17) from Andrew Howroyd, Mar 27 2021

A006404 Number of sensed 2-connected maps with n edges and without faces of degree 2.

Original entry on oeis.org

1, 1, 2, 5, 10, 29, 96, 339, 1320, 5473
Offset: 3

Views

Author

N. J. A. Sloane

Keywords

References

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

Links

Crossrefs

Cf. A006384, A006402, A006405 (unsensed).

Extensions

a(11) and a(12) from Sean A. Irvine, Apr 02 2017
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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