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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A129584 Number of unlabeled bi-point-determining graphs: graphs in which no two vertices have the same neighborhoods or the same augmented neighborhoods (the augmented neighborhood of a vertex is the neighborhood of the vertex union the vertex itself).

Original entry on oeis.org

1, 0, 0, 1, 6, 36, 324, 5280, 156088, 8415760
Offset: 1

Views

Author

Ji Li (vieplivee(AT)hotmail.com), May 07 2007

Keywords

Comments

This is the unlabeled case of bi-point-determining graphs, which are basically graphs that are both point-determining (no two vertices have the same neighborhoods) and co-point-determining (graphs whose complements are point-determining)

Crossrefs

Cf. graphs: labeled A006125, unlabeled A000568; connected graphs: labeled A001187, unlabeled A001349; point-determining graphs: labeled A006024, unlabeled A004110; connected point-determining graphs: labeled A092430, unlabeled A004108; connected co-point-determining graphs: labeled A079306, unlabeled A004108; bi-point-determining graphs: labeled A129583, unlabeled A129584; connected bi-point-determining graphs: labeled A129585, unlabeled A129586; phylogenetic trees: labeled A000311, unlabeled A000669.

A327362 Number of labeled connected graphs covering n vertices with at least one endpoint (vertex of degree 1).

Original entry on oeis.org

0, 0, 1, 3, 28, 475, 14646, 813813, 82060392, 15251272983, 5312295240010, 3519126783483377, 4487168285715524124, 11116496280631563128723, 53887232400918561791887118, 513757147287101157620965656285, 9668878162669182924093580075565776
Offset: 0

Views

Author

Gus Wiseman, Sep 04 2019

Keywords

Comments

A graph is covering if the vertex set is the union of the edge set, so there are no isolated vertices.

Crossrefs

The non-connected version is A327227.
The non-covering version is A327364.
Graphs with endpoints are A245797.
Connected covering graphs are A001187.
Connected graphs with bridges are A327071.

Programs

  • Mathematica
    csm[s_]:=With[{c=Select[Subsets[Range[Length[s]],{2}],Length[Intersection@@s[[#]]]>0&]},If[c=={},s,csm[Sort[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
    Table[Length[Select[Subsets[Subsets[Range[n],{2}]],Union@@#==Range[n]&&Length[csm[#]]==1&&Min@@Length/@Split[Sort[Join@@#]]==1&]],{n,0,5}]
  • PARI
    seq(n)={Vec(serlaplace(-x^2/2 + log(sum(k=0, n, 2^binomial(k, 2)*x^k/k! + O(x*x^n))) - log(sum(k=0, n, 2^binomial(k, 2)*(x*exp(-x + O(x^n)))^k/k!))), -(n+1))} \\ Andrew Howroyd, Sep 11 2019

Formula

Inverse binomial transform of A327364.
a(n) = A001187(n) - A059166(n). - Andrew Howroyd, Sep 11 2019

Extensions

Terms a(7) and beyond from Andrew Howroyd, Sep 11 2019

A327377 Triangle read by rows where T(n,k) is the number of labeled simple graphs covering n vertices with exactly k endpoints (vertices of degree 1).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 0, 3, 0, 10, 12, 12, 4, 3, 253, 260, 160, 60, 35, 0, 12068, 9150, 4230, 1440, 480, 66, 15, 1052793, 570906, 195048, 53200, 12600, 2310, 427, 0, 169505868, 63523656, 15600032, 3197040, 585620, 95088, 14056, 1016, 105
Offset: 0

Views

Author

Gus Wiseman, Sep 05 2019

Keywords

Comments

A graph is covering if there are no isolated vertices.

Examples

			Triangle begins:
      1
      0     0
      0     0     1
      1     0     3     0
     10    12    12     4     3
    253   260   160    60    35     0
  12068  9150  4230  1440   480    66    15
		

Crossrefs

Row sums are A006129.
Column k = 0 is A100743.
Column k = n is A123023.
Row sums without the first column are A327227.
The non-covering version is A327369.
The unlabeled version is A327372.

Programs

  • PARI
    Row(n)={ \\ R, U, B are e.g.f. of A055302, A055314, A059167.
      my(U=sum(n=2, n, x^n*sum(k=1, n, stirling(n-2, n-k, 2)*y^k/k!)) + O(x*x^n));
      my(R=sum(n=1, n, x^n*sum(k=1, n, stirling(n-1, n-k, 2)*y^k/k!)) + O(x*x^n));
      my(B=x^2/2 + log(sum(k=0, n, 2^binomial(k, 2)*(x*exp(-x + O(x^n)))^k/k!)));
      my(A=exp(-x + O(x*x^n))*exp(x + U + subst(B-x, x, x*(1-y) + R)));
      Vecrev(n!*polcoef(A, n), n + 1);
    }
    { for(n=0, 8, print(Row(n))) } \\ Andrew Howroyd, Oct 05 2019

Formula

Column-wise inverse binomial transform of A327369.
E.g.f.: exp(-x)*exp(x + U(x,y) + B(x*(1-y) + R(x,y))), where R(x,y) is the e.g.f. of A055302, U(x,y) is the e.g.f. of A055314 and B(x) + x is the e.g.f. of A059167. - Andrew Howroyd, Oct 05 2019

Extensions

Terms a(28) and beyond from Andrew Howroyd, Oct 05 2019

A123551 Triangle read by rows: T(n,k) gives number of unlabeled graphs without endpoints on n nodes and k edges, (n >= 0, 0 <= k <= n(n-1)/2).

Original entry on oeis.org

1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 2, 4, 3, 2, 1, 1, 1, 0, 0, 1, 1, 2, 6, 8, 13, 16, 13, 8, 5, 2, 1, 1, 1, 0, 0, 1, 1, 2, 6, 10, 22, 48, 76, 97, 102, 84, 60, 39, 20, 10, 5, 2, 1, 1, 1, 0, 0, 1, 1, 2, 6, 10, 25, 64, 152, 331, 617, 930, 1173, 1253, 1140
Offset: 0

Views

Author

N. J. A. Sloane, Nov 14 2006

Keywords

Examples

			Triangle begins:
[0] 1;
[1] 1;
[2] 1, 0;
[3] 1, 0, 0, 1;
[4] 1, 0, 0, 1, 1, 1, 1;
[5] 1, 0, 0, 1, 1, 2, 4, 3,  2,  1,  1;
[6] 1, 0, 0, 1, 1, 2, 6, 8, 13, 16, 13, 8, 5, 2, 1, 1;
  ...
		

References

  • R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977.

Crossrefs

Row sums are A004110.
Cf. A008406, A240168, A369928 (labeled).

Programs

  • PARI
    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)^g )) * prod(i=1, #v, my(c=v[i]); t(c)^((c-1)\2)*if(c%2, 1, t(c/2)))}
    row(n) = {my(s=0); sum(k=0, n, forpart(p=k, s+=permcount(p) * edges(p, w->1+y^w) * y^(n-k)*polcoef(prod(i=1, #p, 1-x^p[i]), n-k)/k!)); Vecrev(s, binomial(n,2)+1)}
    { for(n=0, 6, print(row(n))) } \\ Andrew Howroyd, Feb 07 2024

Formula

T(n,k) = A008406(n,k) - A240168(n,k). - Andrew Howroyd, Apr 16 2021

A129583 Number of labeled bi-point-determining graphs with n vertices.

Original entry on oeis.org

1, 1, 0, 0, 12, 312, 13824, 1147488, 178672128, 52666091712, 29715982846848, 32452221242518272, 69259424722321036032, 291060255757818125657088, 2421848956937579216663491584, 40050322614433939228627991906304, 1319551659023608317386779165849208832
Offset: 0

Views

Author

Ji Li (vieplivee(AT)hotmail.com), May 07 2007

Keywords

Comments

A bi-point determining graph is a graph in which no two vertices have the same neighborhoods or the same augmented neighborhoods (the augmented neighborhood of a vertex is the neighborhood of the vertex union the vertex itself).

References

  • R. C. Read, The Enumeration of Mating-Type Graphs. Report CORR 89-38, Dept. Combinatorics and Optimization, Univ. Waterloo, 1989.

Crossrefs

Cf. graphs: labeled A006125, unlabeled A000568; connected graphs: labeled A001187, unlabeled A001349; point-determining graphs: labeled A006024, unlabeled A004110; connected point-determining graphs: labeled A092430, unlabeled A004108; connected co-point-determining graphs: labeled A079306, unlabeled A004108; bi-point-determining graphs: labeled A129583, unlabeled A129584; connected bi-point-determining graphs: labeled A129585, unlabeled A129586; phylogenetic trees: labeled A000311, unlabeled A000669.

Programs

  • PARI
    seq(n)={my(g=sum(k=0, n, 2^binomial(k,2)*x^k/k!) + O(x*x^n)); Vec(serlaplace(subst(g, x, 2*log(1+x+O(x*x^n))-x)))} \\ Andrew Howroyd, May 06 2021

Formula

E.g.f.: G(2*log(1+x)-x) where G(x) is the e.g.f. of A006125.

Extensions

a(0)=1 prepended and terms a(13) and beyond from Andrew Howroyd, May 06 2021

A129585 Number of labeled connected bi-point-determining graphs with n vertices (see A129583).

Original entry on oeis.org

1, 1, 0, 0, 12, 252, 12312, 1061304, 170176656, 51134075424, 29204599254624, 32130964585236096, 68873851786953047040, 290164895151435531345024, 2417786648013402212500060416, 40014055814155246577685250570752, 1318911434129029730677931158374449664
Offset: 0

Views

Author

Ji Li (vieplivee(AT)hotmail.com), May 07 2007

Keywords

Comments

The calculation of connected bi-point-determining graphs is carried out by examining the connected components of bi-point-determining graphs. For more details, see reference.

Crossrefs

Cf. graphs: labeled A006125, unlabeled A000568; connected graphs: labeled A001187, unlabeled A001349; point-determining graphs: labeled A006024, unlabeled A004110; connected point-determining graphs: labeled A092430, unlabeled A004108; connected co-point-determining graphs: labeled A079306, unlabeled A004108; bi-point-determining graphs: labeled A129583, unlabeled A129584; connected bi-point-determining graphs: labeled A129585, unlabeled A129586; phylogenetic trees: labeled A000311, unlabeled A000669.

Programs

  • Mathematica
    max = 15; f[x_] := x + Log[ Sum[ 2^Binomial[n, 2]*((2*Log[1 + x] - x)^n/n!), {n, 0, max}]/(1 + x)]; A129585 = Drop[ CoefficientList[ Series[ f[x], {x, 0, max}], x]*Range[0, max]!, 1](* Jean-François Alcover, Jan 13 2012, after e.g.f. *)
  • PARI
    seq(n)={my(g=sum(k=0, n, 2^binomial(k,2)*x^k/k!) + O(x*x^n)); Vec(serlaplace(1+x+log(subst(g, x, 2*log(1+x+O(x*x^n))-x)/(1+x))))} \\ Andrew Howroyd, May 06 2021

Formula

E.g.f.: 1 + x + log((Sum_{n>=0} 2^binomial(n,2)*(2*log(1+x)-x)^n/n!)/(1+x)). - Goran Kilibarda, Vladeta Jovovic, May 09 2007
E.g.f.: 1 + x + log(B(x)/(1+x)) where B(x) is the e.g.f. of A129583. - Andrew Howroyd, May 06 2021

Extensions

More terms from Goran Kilibarda, Vladeta Jovovic, May 09 2007
a(0)=1 prepended and terms a(16) and beyond from Andrew Howroyd, May 06 2021

A129586 Number of unlabeled connected bi-point-determining graphs (see A129583).

Original entry on oeis.org

1, 0, 0, 1, 5, 31, 293, 4986, 151096, 8264613, 812528493, 144251345591, 46649058611515, 27744159658789435, 30603223477819571330, 63039669933956074333128, 243839768084859914114367906, 1779006737976575676931317142360, 24571827603944282248499044846893618
Offset: 1

Views

Author

Ji Li (vieplivee(AT)hotmail.com), May 07 2007

Keywords

Comments

The calculation of the number of connected bi-point-determining graphs is carried out by examining the connected components of bi-point-determining graphs. For more details, see linked paper "Enumeration of point-determining Graphs".

Crossrefs

Cf. graphs: labeled A006125, unlabeled A000568; connected graphs: labeled A001187, unlabeled A001349; point-determining graphs: labeled A006024, unlabeled A004110; connected point-determining graphs: labeled A092430, unlabeled A004108; connected co-point-determining graphs: labeled A079306, unlabeled A004108; bi-point-determining graphs: labeled A129583, unlabeled A129584; connected bi-point-determining graphs: labeled A129585, unlabeled A129586; phylogenetic trees: labeled A000311, unlabeled A000669.

Extensions

151096 and 8264613 from Vladeta Jovovic, May 10 2007
a(n) for n >= 11 from Martin Rubey, May 08 2025

A327372 Triangle read by rows where T(n,k) is the number of unlabeled simple graphs covering n vertices with exactly k endpoints (vertices of degree 1).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 3, 1, 1, 1, 1, 11, 5, 4, 1, 2, 0, 62, 29, 18, 6, 4, 2, 1, 510, 225, 101, 32, 13, 4, 3, 0, 7459, 2674, 842, 223, 72, 19, 9, 3, 1, 197867, 50834, 10784, 2171, 504, 115, 34, 9, 4, 0, 9808968, 1653859, 228863, 32322, 5268, 944, 209, 46, 16, 4, 1
Offset: 0

Views

Author

Gus Wiseman, Sep 04 2019

Keywords

Examples

			Triangle begins:
   1
   0  0
   0  0  1
   1  0  1  0
   3  1  1  1  1
  11  5  4  1  2  0
		

Crossrefs

Row sums are A002494.
Column k = 0 is A261919.
The non-covering version is A327371.
The labeled version is A327377.

Programs

  • PARI
    \\ Needs G(n) defined in A327371.
    T(n)={my(v=Vec(G(n)*(1 - x))); vector(#v, n, Vecrev(v[n], n))}
    my(A=T(10)); for(n=1, #A, print(A[n])) \\ Andrew Howroyd, Jan 11 2024

Formula

Column-wise first differences of A327371.

Extensions

Terms a(21) and beyond from Andrew Howroyd, Sep 11 2019

A232699 Number of labeled point-determining bipartite graphs on n vertices.

Original entry on oeis.org

1, 1, 1, 3, 15, 135, 1875, 38745, 1168545, 50017905, 3029330745, 257116925835, 30546104308335, 5065906139629335, 1172940061645387035, 379092680506164049425, 171204492289446788997825, 108139946568584292606269025, 95671942593719946611454522225
Offset: 0

Views

Author

Justin M. Troyka, Nov 27 2013

Keywords

Comments

A graph is point-determining if no two vertices have the same set of neighbors. This kind of graph is also called a mating graph.
a(n) is always odd.
For every prime p > 2, a(n) is divisible by p for all n >= p. It follows that, if m is odd and squarefree with largest prime factor q, then a(n) is divisible by m for all n >= q. A similar property appears to hold for odd prime powers, in which case it would hold for all odd numbers.

Examples

			Consider n = 3. The triangle graph is point-determining, but it is not bipartite, so it is not counted in a(3). The graph 1--2--3 is bipartite, but it is not point-determining (the vertices on the two ends have the same neighborhood), so it is also not counted in a(3). The only graph counted in a(3) is the graph *--*  * (with three possible labelings). - _Justin M. Troyka_, Nov 27 2013
		

Crossrefs

Cf. A006024, A004110 (labeled and unlabeled point-determining graphs).
Cf. A092430, A004108 (labeled and unlabeled connected point-determining graphs).
Cf. A218090 (unlabeled point-determining bipartite graphs).
Cf. A232700, A088974 (labeled and unlabeled connected point-determining bipartite graphs).

Programs

  • Mathematica
    terms = 20;
    CoefficientList[Sqrt[Sum[((1+x)^2^k Log[1+x]^k)/k!, {k, 0, terms}]] + O[x]^terms, x] Range[0, terms-1]! (* Jean-François Alcover, Sep 13 2018, after Andrew Howroyd *)
  • PARI
    seq(n)={my(A=log(1+x+O(x*x^n))); Vec(serlaplace(sqrt(sum(k=0, n, exp(2^k*A)*A^k/k!))))} \\ Andrew Howroyd, Sep 09 2018

Formula

From Andrew Howroyd, Sep 09 2018: (Start)
a(n) = Sum_{k=0..n} Stirling1(n,k)*A047864(k).
E.g.f: sqrt(Sum_{k=0..n} exp(2^k*log(1+x))*log(1+x)^k/k!). (End)

A232700 Number of labeled connected point-determining bipartite graphs on n vertices.

Original entry on oeis.org

1, 1, 0, 12, 60, 1320, 26880, 898800, 40446000, 2568736800, 225962684640, 27627178692960, 4686229692144000, 1104514965434200320, 361988888631722352000, 165271302775469812521600, 105278651889065640047462400, 93750696652129931568573619200
Offset: 1

Views

Author

Justin M. Troyka, Nov 27 2013

Keywords

Comments

A graph is point-determining if no two vertices have the same set of neighbors. This kind of graph is also called a mating graph.
For all n >= 3, a(n) is even. For every prime p > 2, a(n) is divisible by p for all n >= p. It follows that, if m is squarefree with largest prime factor q, then a(n) is divisible by m for all n >= q. A similar property appears to hold for prime powers, in which case it would hold for all numbers.

Examples

			Consider n = 4.  There are 12 connected point-determining bipartite graphs on 4 vertices: the graph *--*--*--*, with 12 possible labelings. - _Justin M. Troyka_, Nov 27 2013
		

Crossrefs

Cf. A006024, A004110 (labeled and unlabeled point-determining graphs).
Cf. A092430, A004108 (labeled and unlabeled connected point-determining graphs).
Cf. A232699, A218090 (labeled and unlabeled point-determining bipartite graphs).
Cf. A088974 (unlabeled connected point-determining bipartite graphs).

Programs

  • Mathematica
    terms = 18;
    G[x_] = Sqrt[Sum[((1 + x)^2^k*Log[1 + x]^k)/k!, {k, 0, terms+1}]] + O[x]^(terms+1);
    A[x_] = x + Log[1 + (G[x] - x - 1)/(1 + x)];
    (CoefficientList[A[x], x]*Range[0, terms]!) // Rest (* Jean-François Alcover, Sep 13 2018, after Andrew Howroyd *)
  • PARI
    seq(n)={my(A=log(1+x+O(x*x^n))); my(p=sqrt(sum(k=0, n, exp(2^k*A)*A^k/k!))); Vec(serlaplace(x + log(1+(p-x-1)/(1+x))))} \\ Andrew Howroyd, Sep 09 2018

Formula

E.g.f.: x + log(1 + (G(x)-x-1)/(1+x)) where G(x) is the e.g.f. of A232699. - Andrew Howroyd, Sep 09 2018
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