A050927 -id:A050927 - cp's OEIS frontend

A138107 Infinite square array: T(n,k) = number of directed multigraphs with loops with n arcs and k vertices; read by falling antidiagonals.

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 2, 6, 1, 0, 1, 2, 10, 10, 1, 0, 1, 2, 11, 31, 19, 1, 0, 1, 2, 11, 47, 90, 28, 1, 0, 1, 2, 11, 51, 198, 222, 44, 1, 0, 1, 2, 11, 52, 269, 713, 520, 60, 1, 0, 1, 2, 11, 52, 291, 1270, 2423, 1090, 85, 1, 0, 1, 2, 11, 52, 295, 1596, 5776, 7388, 2180, 110, 1, 0

Offset: 0

Benoit Jubin, May 03 2008

Partial sums of the rows of A136564.

			The array begins:
   1, 1,   1,    1,     1,     1,     1,     1,     1, ...
   0, 1,   2,    2,     2,     2,     2,     2,     2, ...
   0, 1,   6,   10,    11,    11,    11,    11,    11, ...
   0, 1,  10,   31,    47,    51,    52,    52,    52, ...
   0, 1,  19,   90,   198,   269,   291,   295,   296,  296, ...
   0, 1,  28,  222,   713,  1270,  1596,  1697,  1719, 1723, ...
   0, 1,  44,  520,  2423,  5776,  8838, 10425, 10922, ...
   0, 1,  60, 1090,  7388, 24032, 46384, ...
   0, 1,  85, 2180, 21003, 93067, ...
   0, 1, 110, 4090, ...
   ...

Andrew Howroyd, Table of n, a(n) for n = 0..1325
R. J. Mathar, Statistics on Small Graphs, arXiv:1709.09000 [math.CO] (2017) Table 79.

Columns k=0..4 are: A000007, A000012, A005993, A050927, A050929.
Main diagonal is A362387.
Cf. A052171, A136564, A333361.

permcount(v) = {my(m=1,s=0,k=0,t); for(i=1,#v,t=v[i]; k=if(i>1&&t==v[i-1],k+1,1); m*=t*k;s+=t); s!/m}
edges(v,t) = {prod(i=2, #v, prod(j=1, i-1, my(g=gcd(v[i],v[j])); t(v[i]*v[j]/g)^(2*g))) * prod(i=1, #v, t(v[i])^v[i])}
G(n, x)={my(s=0); forpart(p=n, s+=permcount(p)/edges(p,i->1-x^i)); s/n!}
T(n)={Mat(vector(n+1, k, Col(O(y*y^n) + G(k-1, y + O(y*y^n)))))}
{my(A=T(10)); for(n=1, #A, print(A[n,]))} \\ Andrew Howroyd, Oct 22 2019

T(n,k) = Sum_{p=0..k} A136564(n,p).

If k >= 2n, T(n,k) = A052171(n).

More terms from Vladeta Jovovic and Benoit Jubin, Sep 10 2008

A052171 Number of directed multigraphs with loops on an infinite set of nodes containing a total of n arcs.

Original entry on oeis.org

1, 2, 11, 52, 296, 1724, 11060, 74527, 533046, 3999187, 31412182, 257150093, 2188063401, 19299062896, 176059781439, 1657961491087, 16089088019098, 160643776819423, 1648068916722737, 17351137043998280, 187255329043638437, 2069426416836401375, 23397468305569068113, 270406562951254606048, 3191908298072118225550, 38454691427657997701136

Offset: 0

Vladeta Jovovic, Jan 26 2000

nonn

Row sums of A136564, limiting values of A138107. - Benoit Jubin, May 13 2008

Euler transform of A137975. - M. F. Hasler, Jul 31 2017

Andrew Howroyd, Table of n, a(n) for n = 0..50
Banglei Guan, Ji Zhao, and Laurent Kneip, Six-Point Method for Multi-Camera Systems with Reduced Solution Space, arXiv:2402.18066 [cs.CV], 2024. See p. 10.
J.-C. Novelli, J.-Y. Thibon and N. M. Thiery, Algèbres de Hopf de graphes, C.R. Acad. Sci. Paris (Comptes Rendus Mathématique), 339 (2004), 607-610.
Sanjaye Ramgoolam, Permutation Invariant Gaussian Matrix Models, arXiv:1809.07559 [hep-th], 2018.

Cf. A050535, A007717, A005993, A050927, A050929.

Cf. A104209. Cf. A137975 (connected).

a(n) = A138107(2*n,n). - Max Alekseyev, Oct 17 2017

a(16)-a(25) from Max Alekseyev, Jun 21 2011

A136564 Array read by rows: T(n,k) is the number of directed multigraphs with loops with n arcs, k vertices, and no vertex of degree 0.

Original entry on oeis.org

1, 1, 1, 5, 4, 1, 1, 9, 21, 16, 4, 1, 1, 18, 71, 108, 71, 22, 4, 1, 1, 27, 194, 491, 557, 326, 101, 22, 4, 1, 1, 43, 476, 1903, 3353, 3062, 1587, 497, 111, 22, 4, 1, 1, 59, 1030, 6298, 16644, 22352, 17035, 7982, 2433, 555, 111, 22, 4, 1, 1, 84, 2095, 18823, 72064

Offset: 1

Benoit Jubin, Apr 14 2008

Length of the n^th row: 2n.

			1, 1;
1, 5, 4, 1;
1, 9, 21, 16, 4, 1;
1, 18, 71, 108, 71, 22, 4, 1;
1, 27, 194, 491, 557, 326, 101, 22, 4, 1;
1, 43, 476, 1903, 3353, 3062, 1587, 497, 111, 22, 4, 1;
1, 59, 1030, 6298, 16644, 22352, 17035, 7982, 2433, 555, 111, 22, 4, 1;

Row sums: A052171. Partial row sums: A138107.

Sums of the first m entries of each row: A005993 (m=2), A050927 (m=3), A050929 (m=4).

T(n,1) = 1 if n > 0.
T(n,2n) = 1 if n > 0.
T(n,2n-1) = 4 if n >= 2.
T(n,2n-k) = A144047(k) for n large enough (conjecturally, n >= 2k is enough).
T(n,2) = (n^3 + 6*n^2 + 11*n - 6)/12 + ((n+2)/4)[n even]. (the bracket means that the second term is added if and only if n is even). - Benoit Jubin, Mar 31 2012

More terms from Benoit Jubin and Vladeta Jovovic, Sep 08 2008

A139625 Table read by rows: T(n,k) is the number of strongly connected directed multigraphs with loops and no vertex of degree 0, with n arcs and k vertices, which are transitive (the existence of a path between two points implies the existence of an arc between those two points).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 1, 6, 1, 10, 1, 19, 1, 28, 1, 1, 44, 2, 1, 60, 10, 1, 85, 31, 1, 110, 90, 1, 146, 222, 1, 182, 520, 1, 231, 1090, 1, 1, 280, 2180, 2, 1, 344, 4090, 11, 1

Offset: 1

Benoit Jubin, May 01 2008, Sep 01 2008

Length of the n^th row: floor(sqrt(n)).
These graphs are reflexive (each vertex has a self-loop), so T(n,k) = sum(A139621(n-k^2,m),m=0..k)
T(n,1) = 1, T(n,2) = A005993(n-4), T(n,3) = A050927(n-9), T(n,4) = A050929(n-16).
Row sums: A139630.

			Triangle begins:
  1
  1
  1
  1  1
  1  2
  1  6
  1 10
  1 19
  1 28  1

Cf. A139623, A139624.

cp's OEIS Frontend

A138107 Infinite square array: T(n,k) = number of directed multigraphs with loops with n arcs and k vertices; read by falling antidiagonals.

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A052171 Number of directed multigraphs with loops on an infinite set of nodes containing a total of n arcs.

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A136564 Array read by rows: T(n,k) is the number of directed multigraphs with loops with n arcs, k vertices, and no vertex of degree 0.

Views

Author

Keywords

Comments

Examples

Crossrefs

Formula

Extensions

A139625 Table read by rows: T(n,k) is the number of strongly connected directed multigraphs with loops and no vertex of degree 0, with n arcs and k vertices, which are transitive (the existence of a path between two points implies the existence of an arc between those two points).

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