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.

Showing 1-3 of 3 results.

A000109 Number of simplicial polyhedra with n vertices; simple planar graphs with n vertices and 3n-6 edges; maximal simple planar graphs with n vertices; planar triangulations with n vertices; triangulations of the sphere with n vertices; 3-connected cubic planar graphs on 2n-4 vertices.

Original entry on oeis.org

1, 1, 1, 2, 5, 14, 50, 233, 1249, 7595, 49566, 339722, 2406841, 17490241, 129664753, 977526957, 7475907149, 57896349553, 453382272049, 3585853662949, 28615703421545
Offset: 3

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Keywords

Comments

Every planar triangulation on n >= 4 vertices is 3-connected (the connectivity either 3, 4, or 5) and its dual graph is a 3-connected cubic planar graph on 2n-4 vertices. - Manfred Scheucher, Mar 17 2023

References

  • G. Brinkmann and Brendan McKay, in preparation. [Looking at http://users.cecs.anu.edu.au/~bdm/publications.html, there are a few papers with Brinkmann that seem relevant, in particular #126 but also #97, 81, 158. Perhaps the right one is 126.]
  • M. B. Dillencourt, Polyhedra of small orders and their Hamiltonian properties. Tech. Rep. 92-91, Info. and Comp. Sci. Dept., Univ. Calif. Irvine, 1992.
  • C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979.
  • B. Grünbaum, Convex Polytopes. Wiley, NY, 1967, p. 424.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Formula

From William P. Orrick, Apr 07 2021: (Start)
a(n) >= A007816(n-3)/n! = binomial(n,2)*(4*n-11)!/(n!*(3*n-6)!) for all n >= 4.
a(n) ~ A007816(n-3)/n! = binomial(n,2)*(4*n-11)!/(n!*(3*n-6)!) ~ (1/64)*sqrt(1/(6*Pi))*n^(-7/2)*(256/27)^(n-2), using the theorem that the automorphism group of a maximal planar graph is almost certainly trivial as n gets large. (Tutte)
(End)

Extensions

Extended by Brendan McKay and Gunnar Brinkmann using their program "plantri", Dec 19 2000
Definition clarified by Manfred Scheucher, Mar 17 2023

A288265 Triangle read by rows: T(n,k) is the number of labeled connected planar graphs on n vertices and k edges.

Original entry on oeis.org

1, 1, 3, 1, 16, 15, 6, 1, 125, 222, 205, 120, 45, 10, 1296, 3660, 5700, 6165, 4935, 2937, 1125, 195, 16807, 68295, 156555, 258125, 330456, 334530, 254275, 131985, 40950, 5712, 262144, 1436568, 4483360, 10230360, 18528216, 27261192, 31761744, 27958920, 17666320, 7513632, 1922760, 223440, 4782969, 33779340, 136368414, 405918324, 970196283, 1910996136, 3058785990, 3866563764, 3754432899, 2724326136, 1425385584, 507370500, 109907280, 10929600
Offset: 1

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Author

Gheorghe Coserea, Aug 14 2017

Keywords

Comments

Row n >= 3 contains 3*n-5 terms.

Examples

			A(x;t) = x + t*x^2/2! + (3*t^2 + t^3)*x^3/3! + (16*t^3 + 15*t^4 + 6*t^5 + t^6)*x^4/4! + ...
Triangle starts:
n\k [0] [1] [2] [3] [4]  [5]   [6]   [7]   [8]   [9]   [10]  [11]  [12]
[1] 1;
[2] 0   1;
[3] 0,  0,  3,  1;
[4] 0,  0,  0,  16, 15,  6,    1;
[5] 0,  0,  0,  0,  125, 222,  205,  120,  45,   10;
[6] 0,  0,  0,  0,  0,   1296, 3660, 5700, 6165, 4935, 2937, 1125, 195;
[7] ...
		

Crossrefs

Programs

  • PARI
    Q(n,k) = { \\ c-nets with n-edges, k-vertices
      if (k < 2+(n+2)\3 || k > 2*n\3, return(0));
      sum(i=2, k, sum(j=k, n, (-1)^((i+j+1-k)%2)*binomial(i+j-k,i)*i*(i-1)/2*
      (binomial(2*n-2*k+2,k-i)*binomial(2*k-2, n-j) -
      4*binomial(2*n-2*k+1, k-i-1)*binomial(2*k-3, n-j-1))));
    };
    A100960_ser(N) = {
    my(x='x+O('x^(3*N+1)), t='t+O('t^(N+4)),
       q=t*x*Ser(vector(3*N+1, n, Polrev(vector(min(N+3, 2*n\3), k, Q(n,k)),'t))),
       d=serreverse((1+x)/exp(q/(2*t^2*x) + t*x^2/(1+t*x))-1),
       g2=intformal(t^2/2*((1+d)/(1+x)-1)));
       serlaplace(Ser(vector(N, n, subst(polcoeff(g2, n,'t),'x,'t)))*'x);
    };
    A288265_ser(N) = {
      my(x='x+O('x^(N+3)), b = t*x^2/2 + serconvol(A100960_ser(N), exp(x)),
         g1=intformal(serreverse(x/exp(b'))/x)); serlaplace(g1);
    };
    A288265_seq(N) = {
      my(v=Vec(A288265_ser(N))); vector(#v, n, Vecrev(v[n]/t^(n-1)));
    };
    concat(A288265_seq(9))

Formula

A096332(n) = Sum_{k=n-1..3*n-6} T(n,k) for n >= 3.
A000272(n) = T(n,n-1), A007816(n-3) = T(n, 3*n-6).

A288266 Triangle read by rows: T(n,k) is the number of labeled planar graphs on n vertices and k edges.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 3, 1, 1, 6, 15, 20, 15, 6, 1, 1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1, 15, 105, 455, 1365, 3003, 5005, 6435, 6435, 4995, 2937, 1125, 195, 1, 21, 210, 1330, 5985, 20349, 54264, 116280, 203490, 293860, 351225, 342405, 255640, 131985, 40950, 5712, 1, 28, 378, 3276, 20475, 98280, 376740, 1184040, 3108105, 6906620, 13112694, 21322812, 29332947, 32823084, 28286520, 17712016, 7513632, 1922760, 223440
Offset: 0

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Author

Gheorghe Coserea, Aug 14 2017

Keywords

Comments

Row n >= 3 contains 3*n-5 terms.

Examples

			A(x;t) = 1 + x + (1+t)*x^2/2! + (1+3*t+3*t^2+t^3)*x^3/3! + (1+6*t+15*t^2+20*t^3+15*t^4+6*t^5+t^6)*x^4/4! + ...
Triangle starts:
n\k [0] [1] [2]  [3]  [4]   [5]   [6]   [7]   [8]   [9]   [10]  [11]  [12]
[0] 1;
[1] 1;
[2] 1   1;
[3] 1,  3,  3,   1;
[4] 1,  6,  15,  20,  15,   6,    1;
[5] 1,  10, 45,  120, 210,  252,  210,  120,  45,   10;
[6] 1,  15, 105, 455, 1365, 3003, 5005, 6435, 6435, 4995, 2937, 1125, 195;
[7] ...
		

Crossrefs

Programs

  • PARI
    Q(n,k) = { \\ c-nets with n-edges, k-vertices
      if (k < 2+(n+2)\3 || k > 2*n\3, return(0));
      sum(i=2, k, sum(j=k, n, (-1)^((i+j+1-k)%2)*binomial(i+j-k,i)*i*(i-1)/2*
      (binomial(2*n-2*k+2,k-i)*binomial(2*k-2, n-j) -
      4*binomial(2*n-2*k+1, k-i-1)*binomial(2*k-3, n-j-1))));
    };
    A100960_ser(N) = {
    my(x='x+O('x^(3*N+1)), t='t+O('t^(N+4)),
       q=t*x*Ser(vector(3*N+1, n, Polrev(vector(min(N+3, 2*n\3), k, Q(n,k)),'t))),
       d=serreverse((1+x)/exp(q/(2*t^2*x) + t*x^2/(1+t*x))-1),
       g2=intformal(t^2/2*((1+d)/(1+x)-1)));
       serlaplace(Ser(vector(N, n, subst(polcoeff(g2, n,'t),'x,'t)))*'x);
    };
    A288266_seq(N) = {
      my(x='x+O('x^(N+3)), b=t*x^2/2 + serconvol(A100960_ser(N), exp(x)),
         g1=intformal(serreverse(x/exp(b'))/x));
      apply(p->Vecrev(p), Vec(serlaplace(exp(g1))));
    };
    concat(A288266_seq(8))

Formula

A066537(n) = Sum_{k=0..3*n-6} T(n,k) for n >= 3.
A007816(n-3) = T(n, 3*n-6).
Showing 1-3 of 3 results.