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.

A007561 Number of asymmetric rooted connected graphs where every block is a complete graph.

Original entry on oeis.org

0, 1, 1, 1, 3, 6, 16, 43, 120, 339, 985, 2892, 8606, 25850, 78347, 239161, 734922, 2271085, 7054235, 22010418, 68958139, 216842102, 684164551, 2165240365, 6871792256, 21865189969, 69737972975, 222915760126, 714001019626, 2291298553660, 7366035776888
Offset: 0

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Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column k=2 of A316101.

Programs

  • Maple
    g:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(a(i), j)*g(n-i*j, i-1), j=0..n/i)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(g(i, i), j)*b(n-i*j, i-1), j=0..n/i)))
        end:
    a:= n-> `if`(n<1, 0, b(n-1, n-1)):
    seq(a(n), n=0..40); # Alois P. Heinz, May 19 2013
  • Mathematica
    g[n_, i_] := g[n, i] = If[n == 0, 1, If[i<1, 0, Sum[Binomial[a[i], j]*g[n-i*j, i-1], {j, 0, n/i}]]]; b[n_, i_] := b[n, i] = If[n == 0, 1, If[i<1, 0, Sum[Binomial[g[i, i], j]*b[n-i*j, i-1], {j, 0, n/i}]]]; a[n_] := If[n<1, 0, b[n-1, n-1]]; Table[a[n] // FullSimplify, {n, 0, 40}] (* Jean-François Alcover, Feb 11 2014, after Alois P. Heinz *)

Formula

Shifts left when weigh-transform applied twice.
a(n) ~ c * d^n / n^(3/2), where d = 3.382016466020272807429818743..., c = 0.161800727760188847021075748... . - Vaclav Kotesovec, Jul 26 2014

Extensions

Additional comments from Christian G. Bower

A035081 Number of increasing asymmetric rooted connected graphs where every block is a complete graph.

Original entry on oeis.org

1, 1, 1, 7, 27, 167, 1451, 12672, 133356, 1573608, 20731512, 299642958, 4732486932, 81201040470, 1500094187292, 29730606352920, 628968809015766, 14147458062941100, 337143091156288002, 8485143902146640124
Offset: 1

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Author

Christian G. Bower, Nov 15 1998

Keywords

Comments

In an increasing rooted graph nodes are numbered and numbers increase as you move away from root.

Crossrefs

Programs

  • PARI
    EGJ(v)={Vec(serlaplace(prod(k=1, #v, (1 + x^k/k! + O(x*x^#v))^v[k]))-1, -#v)}
    seq(n)={my(v=[1]); for(n=2, n, v=concat([1], EGJ(EGJ(v)))); v} \\ Andrew Howroyd, Sep 11 2018

Formula

Shifts left when EGJ transform applied twice.

A035080 Number of asymmetric connected graphs where every block is a complete graph.

Original entry on oeis.org

1, 1, 0, 0, 0, 0, 1, 3, 7, 21, 60, 168, 472, 1344, 3843, 11104, 32305, 94734, 279708, 831401, 2485877, 7474667, 22589771, 68594611, 209198103, 640591332, 1968920180, 6072766832, 18791062733, 58321579888, 181524367875, 566488767763, 1772261945866, 5557515157647
Offset: 0

Views

Author

Christian G. Bower, Nov 15 1998

Keywords

Crossrefs

Programs

  • Maple
    g:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(b((i-1)$2), j)*g(n-i*j, i-1), j=0..n/i)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(g(i$2), j)*b(n-i*j, i-1), j=0..n/i)))
        end:
    a:= n-> b((n-1)$2)+g(n$2)-add(b((i-1)$2)*g((n-i)$2), i=0..n):
    seq(a(n), n=0..40); # Alois P. Heinz, May 20 2013
  • Mathematica
    g[n_, i_] := g[n, i] = If[n==0, 1, If[i<1, 0, Sum[Binomial[b[i-1, i-1], j]*g[n-i*j, i-1], {j, 0, n/i}]]]; b[n_, i_] := b[n, i] = If[n==0, 1, If[i < 1, 0, Sum[Binomial[g[i, i], j]*b[n-i*j, i-1], {j, 0, n/i}]]]; a[n_] := b[n-1, n-1] + g[n, n] - Sum[b[i-1, i-1]*g[n-i, n-i], {i, 0, n}]; Table[ a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 19 2016, after Alois P. Heinz *)

Formula

G.f.: A(x) = B(x) + C(x) - B(x)*C(x), where B and C are g.f.s of A007561 and A035079, respectively.
a(n) ~ c * d^n / n^(5/2), where d = 3.38201646602027280742981874... (same as for A007561), c = 0.12430588691278777480105... . - Vaclav Kotesovec, Sep 10 2014
Showing 1-3 of 3 results.