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.

User: Keith Briggs

Keith Briggs's wiki page.

Keith Briggs has authored 24 sequences. Here are the ten most recent ones:

A164099 Number of planar graphs with n nodes and chromatic number 2.

Original entry on oeis.org

1, 2, 6, 12, 33, 83, 273, 937, 3983, 18871, 103697, 628245, 4161652, 29372754, 218035754
Offset: 2

Views

Author

Keith Briggs, Aug 10 2009

Keywords

Formula

(Euler transform of A243321) - 1. - Falk Hüffner, May 10 2019

Extensions

Added term 18871 (for n=11), Keith Briggs, Aug 25 2009
a(12)-a(16) from formula by Falk Hüffner, May 10 2019

A164100 Number of planar graphs with n nodes and chromatic number 3.

Original entry on oeis.org

1, 3, 16, 82, 524, 4372, 47057, 618235, 9289491
Offset: 3

Views

Author

Keith Briggs, Aug 10 2009

Keywords

Extensions

Added term 9289491 (for n=11), Keith Briggs, Aug 25 2009

A164101 Number of planar graphs with n nodes and chromatic number 4.

Original entry on oeis.org

1, 4, 26, 214, 2320, 31858, 518697, 9372645
Offset: 4

Views

Author

Keith Briggs, Aug 10 2009

Keywords

Extensions

Added term 9372645 (for n=11), Keith Briggs, Aug 25 2009

A128236 Number of n-node (unlabeled) graphs with girth 3.

Original entry on oeis.org

1, 4, 20, 118, 937, 11936, 272771, 11992996, 1018892793, 165089910412, 50502010570950, 29054155189364119, 31426485955571756316, 64001015703946097640927, 245935864153501211843554826
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Crossrefs

a(n) = A000088(n) - A006785(n).
Cf. A128041, A128042, A128237-A128243.

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128237 Number of n-node (unlabeled) graphs with girth 4.

Original entry on oeis.org

0, 1, 3, 15, 59, 296, 1604, 11303, 102108, 1250114, 20738069, 467523871, 14230096759, 581439661069, 31720637440030
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Crossrefs

Cf. A006785, A006787.
Cf. A128041, A128042, A128236-A128243.

Formula

a(n) = A006785(n) - A006787(n).

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128241 Number of n-node (unlabeled) connected graphs with girth 4.

Original entry on oeis.org

0, 1, 2, 11, 41, 220, 1243, 9368, 89049, 1135894, 19381407, 445505570, 13741579905, 566739127723, 31124921885829
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Crossrefs

Cf. A024607, A126757.
Cf. A128041, A128042, A128236-A128243.

Formula

a(n) = A024607(n) - A126757(n). - Martin Fuller, May 01 2015

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128041 Triangle read by columns: number of n-node (unlabeled) graphs with girth k, for n >= 3, k >= 3.

Original entry on oeis.org

1, 4, 1, 20, 3, 1, 118, 15, 2, 1, 937, 59, 8, 2, 1, 11936, 296, 26, 9, 2, 1, 272771, 1604, 101, 28, 8, 2, 1, 11992996, 11303, 396, 107, 25, 9, 2, 1, 1018892793, 102108, 1744, 376, 92, 29, 9, 2, 1, 165089910412, 1250114, 8531, 1457, 321, 113, 30, 10, 2, 1
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Examples

			Number of n-node (unlabeled) graphs with girth k, for n >= 3, k >= 3.
.k..|.n=........3........4........5........6........7........8........9........10
---------------------------------------------------------------------------------
.0..|...........0........0........0........0........0........0........0.........0
.1..|...........0........0........0........0........0........0........0.........0
.2..|...........0........0........0........0........0........0........0.........0
.3..|...........1........4.......20......118......937....11936...272771..11992996
.4..|...........0........1........3.......15.......59......296.....1604.....11303
.5..|...........0........0........1........2........8.......26......101.......396
.6..|...........0........0........0........1........2........9.......28.......107
.7..|...........0........0........0........0........1........2........8........25
.8..|...........0........0........0........0........0........1........2.........9
.9..|...........0........0........0........0........0........0........1.........2
10..|...........0........0........0........0........0........0........0.........1

Crossrefs

Cf. A128042, A006787, A128236-A128243.

Programs

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128042 Triangle read by columns: number of n-node (unlabeled) connected graphs with girth k, for n >= 3, k >= 3.

Original entry on oeis.org

1, 3, 1, 15, 2, 1, 93, 11, 1, 1, 794, 41, 5, 1, 1, 10850, 220, 16, 6, 1, 1, 259700, 1243, 66, 17, 5, 1, 1, 11706739, 9368, 266, 69, 15, 6, 1, 1, 1006609723, 89049, 1235, 239, 58, 18, 6, 1, 1, 164058686415, 1135894, 6350, 962, 202, 74, 19, 7, 1, 1
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Examples

			Number of n-node (unlabeled) connected graphs with girth k:
.k..|.n=........3........4........5........6........7........8........9........10
---------------------------------------------------------------------------------
.0..|...........0........0........0........0........0........0........0.........0
.1..|...........0........0........0........0........0........0........0.........0
.2..|...........0........0........0........0........0........0........0.........0
.3..|...........1........3.......15.......93......794....10850...259700..11706739
.4..|...........0........1........2.......11.......41......220.....1243......9368
.5..|...........0........0........1........1........5.......16.......66.......266
.6..|...........0........0........0........1........1........6.......17........69
.7..|...........0........0........0........0........1........1........5........15
.8..|...........0........0........0........0........0........1........1.........6
.9..|...........0........0........0........0........0........0........1.........1
10..|...........0........0........0........0........0........0........0.........1
11..|...........0........0........0........0........0........0........0.........0

Links

Crossrefs

Sequences for k=3..6 are A128240, A128241, A128242, A128243.
Cf. A128041, A006787, A128236, A128237, A128238, A128239.
Cf. A325455 (circumference).

Programs

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128238 Number of n-node (unlabeled) graphs with girth 5.

Original entry on oeis.org

0, 0, 1, 2, 8, 26, 101, 396, 1744, 8531, 47803, 308086, 2300756, 19909540, 199365557
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Crossrefs

Cf. A128041, A128042, A128236-A128243.

Programs

  • nauty
    geng -tfq $n | countg -qg5 --ng # Martin Fuller, May 03 2015

Extensions

Corrected and extended by Martin Fuller, May 01 2015

A128239 Number of n-node (unlabeled) graphs with girth 6.

Original entry on oeis.org

0, 0, 0, 1, 2, 9, 28, 107, 376, 1457, 5733, 24385, 110240, 540400, 2867847
Offset: 3

Views

Author

Keith Briggs, May 05 2007

Keywords

Crossrefs

Cf. A128041, A128042, A128236-A128243.

Programs

  • nauty
    geng -tfq $n | countg -qg6 --ng # Martin Fuller, May 03 2015

Extensions

Corrected and extended by Martin Fuller, May 01 2015

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