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 1-8 of 8 results.

A291837 a(n) is the maximal value in row n of triangle A100960.

Original entry on oeis.org

1, 6, 100, 3525, 210861, 20545920, 2516883516, 366723015750, 65231311386780, 13434052797314820, 3068032280097740670, 770387691039763211415, 222066633621598291951425, 69102739152239837029025040, 23037728813031184811224116360
Offset: 3

Views

Author

Gheorghe Coserea, Sep 04 2017

Keywords

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);
    };
    N=15; apply(p->vecmax(Vecrev(p)), Vec(A100960_ser(N+2)))

Formula

a(n) ~ k * n^(-4) * r^n * n!, where k=0.000002389700772064... (A291838) and r=26.1841125556... (A291836) (see Bender link).

A291839 a(n) is the minimal position at which the maximal value of row n appears in row n of triangle A100960.

Original entry on oeis.org

3, 5, 7, 9, 11, 14, 16, 18, 21, 23, 25, 27, 30, 32, 34, 37, 39, 41, 43, 46, 48, 50, 52, 55, 57, 59, 61, 64, 66, 68, 71, 73, 75, 77, 80, 82, 84, 86, 89, 91, 93, 95, 98, 100, 102, 104, 107, 109, 111, 114, 116, 118, 120, 123, 125, 127, 129, 132
Offset: 3

Views

Author

Gheorghe Coserea, Sep 05 2017

Keywords

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);
    };
    A291839_seq(N) = {
      my(g2=apply(Vecrev, Vec(A100960_ser(N+2))), m=apply(vecmax, g2));
      apply(v->vecmin(v)-1, vector(#g2, k, select(v->v==m[k], g2[k], 1)));
    };
    A291839_seq(22)

Formula

a(n) ~ c*n + o(sqrt(n)), where c=2.26287583256262... (A291840).
T(n, a(n)) = max {T(n,k), n <= k <= 3*(n-2) }, where T(n,k) is defined by A100960.

A096331 Number of 2-connected planar graphs on n labeled nodes.

Original entry on oeis.org

1, 10, 237, 10707, 774924, 78702536, 10273189176, 1631331753120, 304206135619160, 65030138045062272, 15659855107404275280, 4191800375194003211360, 1234179902360142341550240, 396280329098426228719121280, 137779269467538258010671193472
Offset: 3

Views

Author

Steven Finch, Aug 02 2004

Keywords

Comments

Recurrence known, see Bodirsky et al.

References

  • Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, p. 419.

Crossrefs

Cf. A066537. Row sums of A100960.

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);
    };
    Vec(subst(A100960_ser(20),'t,1)) \\ Gheorghe Coserea, Aug 10 2017

Formula

a(n) ~ g * n^(-7/2) * r^n * n!, where g=0.00000370445941594... (A291835) and r=26.1841125556... (A291836) (see Bender link). - Gheorghe Coserea, Sep 03 2017

Extensions

More terms from Gheorghe Coserea, Aug 05 2017

A066537 Number of planar graphs on n labeled nodes.

Original entry on oeis.org

1, 1, 2, 8, 64, 1023, 32071, 1823707, 163947848, 20402420291, 3209997749284, 604611323732576, 131861300077834966, 32577569614176693919, 8977083127683999891824, 2726955513946123452637877, 904755724004585279250537376, 325403988657293080813790670641
Offset: 0

Views

Author

Aart Blokhuis (aartb(AT)win.tue.nl), Jan 08 2002

Keywords

Comments

Precise numbers derived from numbers of 3-connected, 2-connected and 1-connected planar labeled graphs. Details and more entries in Bodirsky et al. Some bounds on the asymptotics are known, see e.g. Taraz et al.

References

  • Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, p. 419.

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);
    };
    A096331_seq(N) = Vec(subst(A100960_ser(N+2),'t,1));
    A096332_seq(N) = {
      my(x='x+O('x^(N+3)), b=x^2/2+serconvol(Ser(A096331_seq(N))*x^3, exp(x)));
      Vec(serlaplace(intformal(serreverse(x/exp(b'))/x)));
    };
    A066537_seq(N) = {
      my(x='x+O('x^(N+3)));
      Vec(serlaplace(exp(serconvol(Ser(A096332_seq(N))*'x,exp(x)))));
    };
    A066537_seq(15) \\ Gheorghe Coserea, Aug 10 2017

Formula

Recurrence known, see Bodirsky et al.
a(n) ~ g * n^(-7/2) * gamma^n * n!, where g=0.000004260938569161439...(A266391) and gamma=27.2268777685...(A266390) (see Gimenez and Noy).

Extensions

More terms from Manuel Bodirsky (bodirsky(AT)informatik.hu-berlin.de), Sep 15 2003
Entry revised by N. J. A. Sloane, Jun 17 2006

A291841 a(n) is the number of labeled 2-connected planar graphs with n edges.

Original entry on oeis.org

1, 3, 18, 131, 1180, 12570, 154525, 2150748, 33399546, 571979428, 10699844995, 216921707622, 4734437392728, 110613829184421, 2752971531611715, 72676980383698345, 2027560176161932735, 59579981648921326791, 1838669555339295257097, 59435431024069408426431
Offset: 3

Views

Author

Gheorghe Coserea, Sep 10 2017

Keywords

Crossrefs

Column sums of A100960.

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))));
    };
    seq(N) = {
    my(x='x+O('x^(N+3)), t='t,
       q=t*x*Ser(vector(N, n, Polrev(vector(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)), e2=apply(serlaplace, g2));
       Vec(subst(e2, 't, 1));
    };
    seq(22)

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

Views

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

Views

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).

A291840 Decimal expansion of the constant c in the asymptotic formula for A291839.

Original entry on oeis.org

2, 2, 6, 2, 8, 7, 5, 8, 3, 2, 5, 6, 2, 6, 2, 1, 2, 4, 6, 3, 0, 2, 3, 3, 3, 3, 5, 8, 3, 8, 4, 3, 6, 5, 9, 3, 8, 9, 0, 6, 8, 0, 4, 1, 9, 6, 3, 9, 5, 3, 7, 1, 0, 5, 2, 7, 1, 2, 7, 1, 6, 3, 3, 4, 1, 8, 5, 4, 7, 3, 8, 9, 7, 1, 2, 9, 9, 4, 8
Offset: 1

Views

Author

Gheorghe Coserea, Sep 05 2017

Keywords

Examples

			2.262875832562621246302333358384...
		

Crossrefs

Programs

  • PARI
    x(t)     = (1+3*t)*(1/t-1)^3/16;
    y(t)     = {
      my(y1  = t^2 * (1-t) * (18 + 36*t + 5*t^2),
         y2  = 2 * (3+t) * (1+2*t) * (1+3*t)^2);
      (1+2*t)/((1+3*t) * (1-t)) * exp(-y1/y2) - 1;
    };
    alpha(t) = 144 + 592*t + 664*t^2 + 135*t^3 + 6*t^4 - 5*t^5;
    mu(t)    = {
      my(mu1 = (1+t) * (3+t)^2 * (1+2*t)^2 * (1+3*t)^2 / t^3, y0 = y(t));
      mu1 * y0 / ((1 + y0) * alpha(t));
    };
    N=79; default(realprecision, N+100); t0 = solve(t=.62, .63, y(t)-1);
    c=mu(t0); eval(select(x->(x != "."), Vec(Str(c))[1..-101]))

Formula

Equals mu(A266389), where function t->mu(t) is defined in the PARI code.
Constant c where A291839(n) ~ c*n + o(sqrt(n)).
Showing 1-8 of 8 results.