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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A006403 Number of unsensed 2-connected planar maps with n edges.

Original entry on oeis.org

0, 1, 2, 3, 6, 15, 36, 114, 396, 1565, 6756, 31563, 154370, 785113, 4099948, 21870704, 118624544, 652485364, 3631820462, 20426666644, 115949791342, 663640383400, 3826858500878, 22218232389849, 129802836253994
Offset: 1

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Author

Keywords

Comments

The maps considered here may include parallel edges. - Andrew Howroyd, Jan 13 2025

References

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

Crossrefs

Row sums of A379432.
Cf. A000139 (rooted), A006385, A006402 (sensed), A006407 (without parallel edges), A006444 (achiral).

Formula

a(n) = (A006402(n) + A006444(n))/2. - Andrew Howroyd, Jan 13 2025

Extensions

a(23)-a(25) added by Andrew Howroyd, Jan 13 2025

A297881 Number of unsensed genus 5 maps with n edges.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1491629, 195728778, 14019733828, 724646387874, 30220873171570, 1079253898643492, 34231899372185491, 988157793188200998, 26412878913430197293, 662133032168309300424, 15719783014093104131694
Offset: 0

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Author

Evgeniy Krasko, Jan 07 2018

Keywords

Crossrefs

Column k=5 of A379439.
Cf. A238355 (rooted), A239918 (sensed).

A006395 Number of unsensed planar maps with n edges and without loops or parallel edges.

Original entry on oeis.org

1, 1, 1, 3, 5, 14, 42, 150, 624, 2947, 15079, 82607, 474030, 2816952, 17194524, 107226255
Offset: 0

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Author

Keywords

Comments

The planar maps considered here are connected. A planar map without loops or parallel edges is called simple.

References

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

Crossrefs

Row sums of A384850, antidiagonal sums of A384963.
Cf. A006385, A006391, A006394 (sensed), A022558 (rooted), A372892 (with n vertices).

Extensions

a(9)-a(12) from Sean A. Irvine, Mar 30 2017
a(0)=1 prepended by Andrew Howroyd, Jan 16 2025
a(13)-a(15) added by Andrew Howroyd, Jun 15 2025

A006391 Number of unsensed loopless planar maps with n edges.

Original entry on oeis.org

1, 1, 2, 5, 14, 45, 191, 871, 4682, 27336, 172706, 1150322, 7989004
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A006385, A000260 (rooted), A006390 (sensed).

Extensions

a(8)-a(12) from Sean A. Irvine, Mar 29 2017
a(0)=1 prepended by Andrew Howroyd, Jan 14 2025

A006405 Number of unsensed 2-connected maps with n edges and without faces of degree 2.

Original entry on oeis.org

1, 1, 2, 5, 9, 24, 70, 222, 785, 3055
Offset: 3

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Author

Keywords

References

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

Crossrefs

Cf. A006385, A006403, A006405 (sensed).

Extensions

a(11) and a(12) from Sean A. Irvine, Apr 02 2017

A006393 Number of unsensed planar maps with n edges and without faces of degree 1 or 2.

Original entry on oeis.org

1, 0, 1, 4, 9, 32, 132, 597, 3064, 17114, 102274, 643907, 4219540
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A006385, A006389, A006392 (sensed), A379434 (rooted).

Extensions

a(8)-a(12) from Sean A. Irvine, Mar 29 2017
a(0)-a(1) prepended by Andrew Howroyd, Jan 16 2025

A006397 Number of unsensed planar maps with n edges and without faces or vertices of degree 1.

Original entry on oeis.org

1, 0, 1, 2, 4, 10, 34, 114, 475, 2104, 10177, 52012, 279874
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A006385, A006389, A006396 (sensed), A379435 (rooted).

Extensions

a(9)-a(12) from Sean A. Irvine, Mar 28 2017
a(0)-a(2) prepended by Andrew Howroyd, Jan 16 2025

A006401 Number of unsensed simple planar maps with n edges and without vertices of degree 1.

Original entry on oeis.org

1, 0, 0, 1, 1, 2, 5, 10, 28, 86, 285, 1055, 4211
Offset: 0

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Author

Keywords

Comments

A simple planar map is a planar map without loops or parallel edges. - Andrew Howroyd, Jan 16 2025

References

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

Crossrefs

Cf. A006385, A006389, A006395, A006400 (sensed), A379436 (rooted).

Extensions

a(11)-a(12) from Sean A. Irvine, Mar 31 2017
a(0)-a(2) prepended by Andrew Howroyd, Jan 16 2025

A006399 Number of unsensed planar maps with n edges and without loops or isthmuses.

Original entry on oeis.org

1, 0, 1, 2, 4, 8, 27, 76, 295, 1188, 5462, 26580, 138110
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A006385, A006391, A006398 (sensed), A099553 (rooted).

Extensions

a(9)-a(12) from Sean A. Irvine, Mar 29 2017
a(0)-a(1) prepended by Andrew Howroyd, Jan 16 2025

A090376 Number of rooted generalized quadrangular dissections of weight n of a closed disk: planar maps having the external face bounded by a polygon and all internal faces of size 4.

Original entry on oeis.org

1, 4, 15, 80, 362, 1832, 8994, 46384, 238838, 1257824
Offset: 0

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Author

Valery A. Liskovets, Dec 03 2003

Keywords

Comments

Some boundary mutually non-adjacent nodes of valency 2 are marked as singular; (boundary) edges incident to them are also called singular. The maps are considered up to rotations and reflections. Rooting means distinguishing a non-singular edge, an end and an internal side of it. n is the number of internal edges plus half of the number of non-singular boundary edges.
No formula is known. For any generalized quadrangular dissection, s==n (mod 2), where s is the number of singular nodes.

Examples

			The four rooted generalized quadrangular dissections of weight 1 are
...................____......____..
.X<---X..X---<X.../....\..../....\.
.|....|..|....|..X<--X..O..X--<X..O
.|....|..|....|...\____/....\____/.
.X----O..X----O....................
where O is the singular node and -> is the rooted edge-end.
		

Crossrefs

Cf. A006385.
Previous Showing 11-20 of 21 results. Next