A185234 -id:A185234 - cp's OEIS frontend

A014371 Number of trivalent connected simple graphs with 2*n nodes and girth at least 4.

1, 0, 0, 1, 2, 6, 22, 110, 792, 7805, 97546, 1435720, 23780814, 432757568, 8542471494, 181492137812, 4127077143862

Offset: 0

The null graph on 0 vertices is vacuously connected and 3-regular; since it is acyclic, it has infinite girth. - Jason Kimberley, Jan 29 2011

CRC Handbook of Combinatorial Designs, 1996, p. 647.

G. Brinkmann, J. Goedgebeur and B. D. McKay, Generation of Cubic graphs, Discrete Mathematics and Theoretical Computer Science, 13 (2) (2011), 69-80. (hal-00990486)
House of Graphs, Cubic graphs.
Jason Kimberley, Connected regular graphs with girth at least 4
Jason Kimberley, Index of sequences counting connected k-regular simple graphs with girth at least g
M. Meringer, Tables of Regular Graphs.
M. Meringer, Fast generation of regular graphs and construction of cages, J. Graph Theory 30 (2) (1999) 137-146.

From Jason Kimberley, Jun 28 2010 and Jan 29 2011: (Start)
3-regular simple graphs with girth at least 4: this sequence (connected), A185234 (disconnected), A185334 (not necessarily connected).
Connected k-regular simple graphs with girth at least 4: A186724 (any k), A186714 (triangle); specified degree k: A185114 (k=2), this sequence (k=3), A033886 (k=4), A058275 (k=5), A058276 (k=6), A181153 (k=7), A181154 (k=8), A181170 (k=9).
Connected 3-regular simple graphs with girth at least g: A185131 (triangle); chosen g: A002851 (g=3), this sequence (g=4), A014372 (g=5), A014374 (g=6), A014375 (g=7), A014376 (g=8).
Connected 3-regular simple graphs with girth exactly g: A198303 (triangle); chosen g: A006923 (g=3), A006924 (g=4), A006925 (g=5), A006926 (g=6), A006927 (g=7). (End)

A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {, }][[All, 2]]];
A002851 = A@002851;
A006923 = A@006923;
a[n_] := A002851[[n + 1]] - A006923[[n + 1]];
a /@ Range[0, 16] (* Jean-François Alcover, Jan 27 2020 *)

Terms a(14) and a(15) appended, from running Meringer's GENREG for 4.2 and 93.2 processor days at U. Newcastle, by Jason Kimberley on Jun 28 2010

a(16), from House of Graphs, by Jan Goedgebeur et al., added by Jason Kimberley, Feb 15 2011

A185224 Number of disconnected 2-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 4, 4, 6, 7, 10, 11, 15, 17, 23, 26, 33, 38, 49, 56, 69, 80, 99, 114, 139, 160, 194, 224, 268, 310, 370, 426, 504, 582, 687, 790, 927, 1066, 1247, 1433, 1667, 1913, 2222, 2545, 2944, 3369, 3888, 4442, 5112, 5833, 6697, 7631, 8739

Offset: 0

Jason Kimberley, Feb 22 2011

a(n) is also the number of partitions of n with each part at least 4 and at most n-1. The integer i corresponds to the i-cycle; addition of integers corresponds to disconnected union of cycles.

Andrew van den Hoeven, Table of n, a(n) for n = 0..1000
Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

2-regular graphs with girth at least 4: A185114 (connected), this sequence (disconnected), A008484 (not necessarily connected).
Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).
Disconnected 2-regular simple graphs with girth at least g [partitions of n with each part i being g <= i < n]: A165652 (g=3), this sequence (g=4), A185225 (g=5), A185226 (g=6), A185227 (g=7), A185228 (g=8), A185229 (g=9).

Magma
```
A185224 := func;
```

a(n) = A008484(n) - A185114(n).

A185214 Number of disconnected regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 2, 1, 3, 2, 4, 3, 7, 5, 10, 8, 22, 12, 54, 20, 218, 62, 1436, 1731, 27810, 197981, 2613814, 33117962, 463707741, 6709514340, 102306352539, 1597440872801

Offset: 0

Jason Kimberley, Mar 26 2012

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

This sequence is the row sum sequence of A185204.
Regular graphs, of any degree, with girth at least 4: A186724 (connected), this sequence (disconnected), A185314 (not necessarily connected).
Disconnected k-regular simple graphs with girth at least 4: this sequence (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

a(31) corrected by the author, propagated from A185244, Jan 05 2013

A185244 Number of disconnected 4-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 2, 15, 35, 247, 1692, 17409, 197924, 2492824, 33117880, 461597957, 6709514218, 101153412903, 1597440868898

Offset: 0

Jason Kimberley, Feb 22 2011

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

4-regular simple graphs with girth at least 4: A033886 (connected), this sequence (disconnected), A185344 (not necessarily connected).
Disconnected 4-regular simple graphs with girth at least g: A033483 (g=3), this sequence (g=4), A185245 (g=5), A185246 (g=6).
Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), this sequence (k=4), A185254 (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

a(n) = A185344(n) - A033886(n) = Euler_transformation(A033886)(n) - A033886(n).

a(n) = A185044(n) + A185245(n).

a(31) appended by the author once A033886(23) was known, Nov 03 2011

a(31) corrected by the author, Jan 05 2013

A185204 Triangular array D(n,k) counting disconnected k-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 0, 2, 1, 1, 4, 1, 1, 0, 4, 0, 1, 1, 6, 2, 1, 0, 7, 0, 1, 1, 10, 9, 1, 1, 0, 11, 0, 0, 1, 1, 15, 35, 2, 1, 0, 17, 0, 2, 1, 1, 23, 177, 15, 1, 1, 0, 26, 0, 35, 0, 1, 1, 33, 1153, 247, 1, 1, 0, 38, 0, 1692, 0, 1, 1, 49, 10341, 17409, 8, 1

Offset: 1

Jason Kimberley, Feb 22 2011

For n >= 0 and 0 <= k <= A002265(n).

			0;
1;
1;
1, 1;
1, 0;
1, 1;
1, 0;
1, 1, 1;
1, 0, 1;
1, 1, 2;
1, 0, 2;
1, 1, 4, 1;
1, 0, 4, 0;
1, 1, 6, 2;
1, 0, 7, 0;
1, 1, 10, 9, 1;
1, 0, 11, 0, 0;
1, 1, 15, 35, 2;
1, 0, 17, 0, 2;

Jason Kimberley, Table of i, a(i)=D(n,k) for i = 1..147 (n = 1..32)
Jason Kimberley, Incomplete table of i, n, k, D(n,k)=a(i) for n = 1..38 (i = 1..209)
Jason Kimberley, Disconnected k-regular graphs with girth at least 4
Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), this sequence (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

The b-file corrected and a-file expanded by the author, Jan 19 2013

A185334 Number of not necessarily connected 3-regular simple graphs on 2n vertices with girth at least 4.

Original entry on oeis.org

1, 0, 0, 1, 2, 6, 23, 112, 801, 7840, 97723, 1436873, 23791155, 432878091, 8544173926, 181519645163, 4127569521160

Offset: 0

Jason Kimberley, Feb 15 2011

The null graph on 0 vertices is vacuously 3-regular; since it is acyclic, it has infinite girth.

Jason Kimberley, Not necessarily connected k-regular graphs with girth at least 4
Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g

3-regular simple graphs with girth at least 4: A014371 (connected), A185234 (disconnected), this sequence (not necessarily connected).
Not necessarily connected k-regular simple graphs with girth at least 4: A185314 (any k), A185304 (triangle); specified degree k: A008484 (k=2), this sequence (k=3), A185344 (k=4), A185354 (k=5), A185364 (k=6).
Not necessarily connected 3-regular simple graphs with girth *at least* g: A005638 (g=3), this sequence (g=4), A185335 (g=5), A185336 (g=6).
Not necessarily connected 3-regular simple graphs with girth *exactly* g: A185133 (g=3), A185134 (g=4), A185135 (g=5), A185136 (g=6).

A014371 = Cases[Import["https://oeis.org/A014371/b014371.txt", "Table"], {, }][[All, 2]];
(* EulerTransform is defined in A005195 *)
EulerTransform[Rest @ A014371] (* Jean-François Alcover, Dec 04 2019, updated Mar 18 2020 *)

Euler transformation of A014371.

A185254 Number of disconnected 5-regular simple graphs on 2n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 8, 395, 407240, 1125431866, 3814677304834

Offset: 0

Jason Kimberley, Feb 22 and Nov 04 2011

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

5-regular simple graphs on 2n vertices with girth at least 4: A058275 (connected), this sequence (disconnected), A185354 (not necessarily connected).

Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), this sequence (k=5), A185264 (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

A185264 Number of disconnected 6-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 10, 7, 277, 3742, 483330, 69827771, 14836620025

Offset: 0

Jason Kimberley, Feb 22 2011

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

6-regular simple graphs with girth at least 4: A058276 (connected), this sequence (disconnected), A185364 (not necessarily connected).

Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), this sequence (k=6), A185274 (k=7), A185284 (k=8), A185294 (k=9).

a(n)
= A185364(n) - A058276(n)
= Euler_transformation(A058276)(n) - A058276(n).

A185033 Number of disconnected 3-regular simple graphs on 2n vertices with girth exactly 3.

Original entry on oeis.org

0, 0, 0, 0, 1, 2, 8, 29, 138, 774, 5678, 53324, 622716, 8604351, 135344959, 2363662004, 45134533117, 933058713014, 20735549517852, 492653820710746

Offset: 0

Jason Kimberley, Feb 29 2012

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth exactly g

Disconnected k-regular simple graphs with girth exactly 3: A210713 (any k), A210703 (triangle); for fixed k: this sequence (k=3), A185043 (k=4), A185053 (k=5), A185063 (k=6).

Disconnected 3-regular simple graphs with girth exactly g: this sequence (g=3), A185034 (g=4), A185035 (g=5), A185036 (g=6), A185037 (g=7).

a(n) = A165653(n) - A185234(n).

A185274 Number of disconnected 7-regular simple graphs on 2n vertices with girth at least 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 9, 749, 2888270

Offset: 0

Jason Kimberley, Feb 22 2011

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g

Disconnected k-regular simple graphs with girth at least 4: A185214 (any k), A185204 (triangle); specified degree k: A185224 (k=2), A185234 (k=3), A185244 (k=4), A185254 (k=5), A185264 (k=6), this sequence (k=7), A185284 (k=8), A185294 (k=9).

cp's OEIS Frontend

A014371 Number of trivalent connected simple graphs with 2*n nodes and girth at least 4.

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A185224 Number of disconnected 2-regular simple graphs on n vertices with girth at least 4.

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A185214 Number of disconnected regular simple graphs on n vertices with girth at least 4.

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A185244 Number of disconnected 4-regular simple graphs on n vertices with girth at least 4.

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A185204 Triangular array D(n,k) counting disconnected k-regular simple graphs on n vertices with girth at least 4.

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A185334 Number of not necessarily connected 3-regular simple graphs on 2n vertices with girth at least 4.

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A185254 Number of disconnected 5-regular simple graphs on 2n vertices with girth at least 4.

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A185264 Number of disconnected 6-regular simple graphs on n vertices with girth at least 4.

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A185033 Number of disconnected 3-regular simple graphs on 2n vertices with girth exactly 3.

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A185274 Number of disconnected 7-regular simple graphs on 2n vertices with girth at least 4.

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