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.

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A006406 Number of sensed 2-connected simple planar maps with n edges.

Original entry on oeis.org

1, 1, 2, 4, 9, 24, 81, 274, 1071, 4357, 18416, 80040, 356109, 1610910, 7399114
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 up to orientation preserving isomorphisms. - 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. A006402, A006404, A006407 (unsensed case), A342059, A379437 (rooted).

Formula

a(n) = Sum_{k=3..n} A342059(k, n+2-k). - Andrew Howroyd, Mar 27 2021

Extensions

a(11) and a(12) from Sean A. Irvine, Apr 02 2017
a(13)-a(17) from Andrew Howroyd, Mar 27 2021
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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