A185344 -id:A185344 - cp's OEIS frontend

A008484 Number of partitions of n into parts >= 4.

1, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 5, 5, 7, 8, 11, 12, 16, 18, 24, 27, 34, 39, 50, 57, 70, 81, 100, 115, 140, 161, 195, 225, 269, 311, 371, 427, 505, 583, 688, 791, 928, 1067, 1248, 1434, 1668, 1914, 2223, 2546, 2945, 3370, 3889, 4443, 5113, 5834, 6698

Offset: 0

T. Forbes (anthony.d.forbes(AT)googlemail.com)

a(n) is also the number of not necessarily connected 2-regular graphs on n-vertices with girth at least 4 (all such graphs are simple). The integer i corresponds to the i-cycle; addition of integers corresponds to disconnected union of cycles. - Jason Kimberley, Jan 2011 and Feb 2012
By removing a single part of size 4, an A026797 partition of n becomes an A008484 partition of n - 4. Hence this sequence is essentially the same as A026797. - Jason Kimberley, Feb 2012
Number of partitions of n+3 such that 3*(number of parts) is a part. - Clark Kimberling, Feb 27 2014
Let c(n) be the number of partitions of n such that both (number of parts) and 2*(number of parts) are parts; then c(n) = a(n-6) for n >= 6 and c(n) = 0 for n < 6. - Clark Kimberling, Mar 01 2014
a(n) is also the number of partitions of n for which three times the number of ones is twice the number of parts (conjectured). - George Beck, Aug 19 2017
Proof: Above definition is equivalent to 2 out of 3 parts being equal to 1. Arrange in triples 1, 1, >= 2, etc. Sum of each triple corresponds to sequence definition. - Martin Fuller, Aug 21 2023

Giovanni Resta, Table of n, a(n) for n = 0..1000
Kevin Beanland and Hung Viet Chu, On Schreier-type Sets, Partitions, and Compositions, arXiv:2311.01926 [math.CO], 2023.
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

2-regular graphs with girth at least 4: A185114 (connected), A185224 (disconnected), this sequence (not necessarily connected).
Not necessarily connected 2-regular graphs with girth at least g [partitions into parts >= g]: A026807 (triangle); chosen g: A000041 (g=1 -- multigraphs with loops allowed), A002865 (g=2 -- multigraphs with loops forbidden), A008483 (g=3), this sequence (g=4), A185325(g=5), A185326 (g=6), A185327 (g=7), A185328 (g=8), A185329 (g=9).
Not necessarily connected 2-regular graphs with girth exactly g [partitions with smallest part g]: A026794 (triangle); chosen g: A002865 (g=2), A026796 (g=3), A026797 (g=4), A026798 (g=5), A026799 (g=6), A026800(g=7), A026801 (g=8), A026802 (g=9), A026803 (g=10).
Not necessarily connected k-regular simple graphs with girth at least 4: A185314 (any k), A185304 (triangle); specified degree k: this sequence (k=2), A185334 (k=3), A185344 (k=4), A185354 (k=5), A185364 (k=6).

a:= func< n | NumberOfPartitions(n)-NumberOfPartitions(n-1)-NumberOfPartitions(n-2)+ NumberOfPartitions(n-4)+NumberOfPartitions(n-5)- NumberOfPartitions(n-6) >; [1,0,0,0,1,1,1] cat [ a(n) : n in [7..60]]; // Vincenzo Librandi, Aug 20 2017

R:=PowerSeriesRing(Integers(), 60); Coefficients(R!( 1/(&*[1-x^(m+4): m in [0..70]]) )); // G. C. Greubel, Nov 03 2019

series(1/product((1-x^i),i=4..65),x,60); # end of program
ZL := [ B,{B=Set(Set(Z, card>=4))}, unlabeled ]: seq(combstruct[count](ZL, size=n), n=0..60); # Zerinvary Lajos, Mar 13 2007

f[1, 1]=1; f[n_, k_]:= f[n, k] = If[n<0, 0, If[k>n, 0, If[k==n, 1, f[n, k +1] + f[n-k, k]]]]; Table[f[n, 4], {n, 60}] (* end of program *)
Drop[Table[Count[IntegerPartitions[n], p_ /; MemberQ[p, 3*Length[p]]], {n, 60}],2]  (* Clark Kimberling, Feb 27 2014 *)
Table[Count[IntegerPartitions[n],
  p_ /; 3 Count[p, 1] == 2 Length[p]], {n, 0, 60}] (* George Beck Aug 19 2017 *)
CoefficientList[Series[1/QPochhammer[x^4, x], {x,0,60}], x] (* G. C. Greubel, Nov 03 2019 *)

my(x='x+O('x^60)); Vec(1/prod(m=0,70, 1-x^(m+4))) \\ G. C. Greubel, Nov 03 2019

def A008484_list(prec):
    P. = PowerSeriesRing(ZZ, prec)
    return P( 1/product((1-x^(m+4)) for m in (0..70)) ).list()
A008484_list(60) # G. C. Greubel, Nov 03 2019

G.f.: 1 / Product_{m>=4} (1 - x^m).
Euler transformation of A185114. - Jason Kimberley, Jan 30 2011
Given by p(n) - p(n-1) - p(n-2) + p(n-4) + p(n-5) - p(n-6) where p(n) = A000041(n). Generally, 1/Product_{i>=K} (1 - x^i) is given by p({A}), where {A} is defined over the coefficients of Product_{i=1..K-1} (1 - x^i). In this case, K=4, so (1-x)(1-x^2)(1-x^3) = 1 - x - x^2 + x^4 + x^5 - x^6, defining {A} as above. G.f.: 1 + Sum_{i>=1} (x^4i)/Product_{j=1..i}(1 - x^j). - Jon Perry, Jul 04 2004
a(n) ~ exp(Pi*sqrt(2*n/3)) * Pi^3 / (12*sqrt(2)*n^(5/2)). - Vaclav Kotesovec, Jun 02 2018
G.f.: exp(Sum_{k>=1} x^(4*k)/(k*(1 - x^k))). - Ilya Gutkovskiy, Aug 21 2018
G.f.: 1 + Sum_{n >= 1} x^(n+3)/Product_{k = 0..n-1} (1 - x^(k+4)). - Peter Bala, Dec 01 2024

A033886 Number of connected 4-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 2, 12, 31, 220, 1606, 16828, 193900, 2452818, 32670330, 456028474, 6636066099, 100135577747, 1582718912968

Offset: 0

N. J. A. Sloane, Dec 17 2000

The null graph on 0 vertices is vacuously connected and 4-regular; since it is acyclic, it has infinite girth. - Jason Kimberley, Jan 29 2011

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.
Markus Meringer, Fast Generation of Regular Graphs and Construction of Cages, Journal of Graph Theory, Vol. 30, No. 2 (1999), 137-146.
Markus Meringer, Tables of Regular Graphs.

From Jason Kimberley, Mar 19 2010 and Jan 28 2011: (Start)
4-regular simple graphs with girth at least 4: this sequence (connected), A185244 (disconnected), A185344 (not necessarily connected).
Connected k-regular simple graphs with girth at least 4: A186724 (any k), A186714 (triangle); specified degree k: A185114 (k=2), A014371 (k=3), this sequence (k=4), A058275 (k=5), A058276 (k=6), A181153 (k=7), A181154 (k=8), A181170 (k=9).
Connected 4-regular simple graphs with girth at least g: A006820 (g=3), this sequence (g=4), A058343 (g=5), A058348 (g=6).
Connected 4-regular simple graphs with girth exactly g: A184943 (g=3), A184944 (g=4), A184945 (g=5). (End)

By running M. Meringer's GENREG at U. Newcastle for 6.25, 107 and 1548 processor days, a(21), a(22), and a(23) were completed by Jason Kimberley on Dec 06 2009, Mar 19 2010, and Nov 02 2011.

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

A185314 Number of, not necessarily connected, regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

1, 1, 2, 1, 3, 2, 4, 2, 7, 3, 14, 6, 44, 37, 350, 1616, 18042, 193919, 2867779, 32674078, 1581632332, 6705889886

Offset: 0

Jason Kimberley, May 23 2012

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

Regular graphs, of any degree, with girth at least 4: A186724 (connected), A185214 (disconnected), this sequence (not-necessarily connected).
Not necessarily connected k-regular simple graphs with girth at least 4: this sequence (any k), A185304 (triangle); specified degree k: A008484 (k=2), A185334 (k=3), A185344 (k=4), A185354 (k=5), A185364 (k=6).
Not necessarily connected regular simple graphs with girth at least g: A005176 (g=3), this sequence (g=4), A185315 (g=5), A185316 (g=6), A185317 (g=7), A185318 (g=8), A185319 (g=9).

a(n) = A186724(n) + A185214(n).

a(n) is the sum of the n-th row of A185304.

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.

A185143 Number of not necessarily connected 4-regular simple graphs on n vertices with girth exactly 3.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 1, 2, 5, 16, 58, 264, 1535, 10755, 87973, 803973, 8020967, 86029760, 983431053, 11913921910, 152352965278, 2050065073002, 28951233955602, 428086557232387

Offset: 0

Jason Kimberley, Mar 12 2012

Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth exactly g

4-regular simple graphs with girth exactly 3: A184943 (connected), A185043 (disconnected), this sequence (not necessarily connected).
Not necessarily connected k-regular simple graphs girth exactly 3: A198313 (any k), A185643 (triangle); fixed k: A026796 (k=2), A185133 (k=3), this sequence (k=4), A185153 (k=5), A185163 (k=6).
Not necessarily connected 4-regular simple graphs with girth exactly g: A185140 (triangle); fixed g: this sequence (g=3), A185144 (g=4).

a(n) = A033301(n) - A185344(n).

a(n) = A184943(n) + A185043(n).

a(22) corrected and a(23) appended, due to the correction and extension of A033301 by Andrew Howroyd, from Jason Kimberley, Mar 14 2020

A185304 Triangular array E(n,k) counting not necessarily connected k-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 2, 2, 1, 1, 0, 2, 0, 0, 1, 1, 3, 6, 2, 1, 1, 0, 3, 0, 2, 0, 1, 1, 5, 23, 12, 1, 1, 1, 0, 5, 0, 31, 0, 0, 1, 1, 7, 112, 220, 7, 1, 1, 1, 0, 8, 0, 1606, 0, 1, 0, 1, 1, 11, 801, 16829, 388, 9, 1, 1, 1, 0, 12, 0, 193900, 0, 6, 0, 0, 1, 1, 16, 7840, 2452820, 406824, 267, 8, 1, 1, 1, 0, 18, 0, 32670332, 0, 3727, 0, 0, 0

Offset: 1

Jason Kimberley, Jan 19 2013

Row sums give A185314.

			1: 1;
2: 1, 1;
3: 1, 0;
4: 1, 1, 1;
5: 1, 0, 1;
6: 1, 1, 1, 1;
7: 1, 0, 1, 0;
8: 1, 1, 2, 2, 1;
9: 1, 0, 2, 0, 0;
10: 1, 1, 3, 6, 2, 1;
11: 1, 0, 3, 0, 2, 0;
12: 1, 1, 5, 23, 12, 1, 1;
13: 1, 0, 5, 0, 31, 0, 0;
14: 1, 1, 7, 112, 220, 7, 1, 1;
15: 1, 0, 8, 0, 1606, 0, 1, 0;
16: 1, 1, 11, 801, 16829, 388, 9, 1, 1;
17: 1, 0, 12, 0, 193900, 0, 6, 0,0;
18: 1, 1, 16, 7840, 2452820, 406824, 267, 8, 1, 1;
19: 1, 0, 18, 0, 32670332, 0, 3727, 0,0, 0;
20: 1, 1, 24, 97723, 456028489, 1125022326, 483012, 741, 13, 1, 1;
21: 1, 0, 27, 0, 6636066134, 0, 69823723, 0, 1, 0, 0;
22: 1, 1, 34, 1436873, 100135577994, 3813549359275, 14836130862, 2887493, ?, 14, 1;

Jason Kimberley, Table of n, a(i)=E(n,k) for i = 1..139 (n = 1..22)
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

Not necessarily connected k-regular simple graphs with girth at least 4: A185314 (any k), this sequence (triangle); specified degree k: A008484 (k=2), A185334 (k=3), A185344 (k=4), A185354 (k=5), A185364 (k=6).

E(n,k) = A186714(n,k) + A185204(n,k).

E(10,2) corrected by the author, Mar 26 2013

a(32)=E(10,2) in b-file corrected as above by Andrew Howroyd, Feb 22 2018

A185354 Number of not necessarily connected 5-regular simple graphs on 2n vertices with girth at least 4.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 7, 388, 406824, 1125022326, 3813549359275

Offset: 0

Jason Kimberley, Nov 04 2011

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

5-regular simple graphs on 2n vertices with girth at least 4: A058275 (connected), A185254 (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), A185334 (k=3), A185344 (k=4), this sequence (k=5), A185364 (k=6).

A058275 = Cases[Import["https://oeis.org/A058275/b058275.txt", "Table"], {, }][[All, 2]];
(* EulerTransform is defined in A005195 *)
EulerTransform[Rest @ A058275]  (* Jean-François Alcover, Dec 04 2019, updated Mar 18 2020 *)

This sequence is the Euler transformation of A058275.

a(n) = A058275(n) + A185254(n).

A185364 Not necessarily connected 6-regular simple graphs on n vertices with girth at least 4.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 9, 6, 267, 3727, 483012, 69823723, 14836130862

Offset: 0

Jason Kimberley, Dec 07 2011

First differs from A058276 at n=24.

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

6-regular simple graphs with girth at least 4: A058276 (connected), A185264 (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), A185334 (k=3), A185344 (k=4), A185354 (k=5), this sequence (k=6).
Cf. A184964.

A058276 = Cases[Import["https://oeis.org/A058276/b058276.txt", "Table"], {, }][[All, 2]];
(* EulerTransform is defined in A005195 *)
EulerTransform[Rest @ A058276] (* Jean-François Alcover, Dec 04 2019, updated Mar 18 2020 *)

This sequence is the Euler transformation of A058276.

a(n) = A058276(n) + A185264(n).

cp's OEIS Frontend

A008484 Number of partitions of n into parts >= 4.

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A033886 Number of connected 4-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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A185314 Number of, not necessarily connected, 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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A185143 Number of not necessarily connected 4-regular simple graphs on n vertices with girth exactly 3.

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A185304 Triangular array E(n,k) counting not necessarily connected k-regular simple graphs on n vertices with girth at least 4.

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A185354 Number of not necessarily connected 5-regular simple graphs on 2n vertices with girth at least 4.

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A185364 Not necessarily connected 6-regular simple graphs on n vertices with girth at least 4.

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