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 1-4 of 4 results.

A035079 Weigh transform of A007561.

Original entry on oeis.org

1, 1, 1, 2, 4, 10, 26, 71, 197, 564, 1639, 4833, 14406, 43374, 131652, 402525, 1238419, 3831520, 11912913, 37204431, 116655147, 367100319, 1159026041, 3670339794, 11655070593, 37104257405, 118398974620, 378627600346, 1213247498254, 3894924465243
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-> g(n, 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_] := g[n, n];
    Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 22 2017, after Alois P. Heinz *)

Formula

a(n) ~ c * d^n / n^(3/2), where d = 3.382016466020272807429818743... (same as for A035080), c = 0.2780120087122189647675707... . - Vaclav Kotesovec, Sep 12 2014

A316101 Sequence a_k of column k shifts left when Weigh transform is applied k times with a_k(n) = n for n<2; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 0, 1, 1, 1, 3, 3, 1, 0, 1, 1, 1, 4, 6, 6, 1, 0, 1, 1, 1, 5, 10, 16, 12, 1, 0, 1, 1, 1, 6, 15, 32, 43, 25, 1, 0, 1, 1, 1, 7, 21, 55, 105, 120, 52, 1, 0, 1, 1, 1, 8, 28, 86, 210, 356, 339, 113, 1, 0, 1, 1, 1, 9, 36, 126, 371, 826, 1227, 985, 247, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 24 2018

Keywords

Examples

			Square array A(n,k) begins:
  0,  0,   0,   0,   0,    0,    0,    0,    0, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  1,   1,   1,   1,    1,    1,    1,    1, ...
  1,  2,   3,   4,   5,    6,    7,    8,    9, ...
  1,  3,   6,  10,  15,   21,   28,   36,   45, ...
  1,  6,  16,  32,  55,   86,  126,  176,  237, ...
  1, 12,  43, 105, 210,  371,  602,  918, 1335, ...
  1, 25, 120, 356, 826, 1647, 2961, 4936, 7767, ...
		

Crossrefs

Rows include (offsets may differ): A000004, A000012, A000027, A000217, A134465.
Main diagonal gives A316102.

Programs

  • Maple
    wtr:= proc(p) local b; b:= proc(n, i) option remember;
           `if`(n=0, 1, `if`(i<1, 0, add(binomial(p(i), j)*
             b(n-i*j, i-1), j=0..n/i))) end: j-> b(j$2)
          end:
    g:= proc(k) option remember; local b, t; b[0]:= j->
         `if`(j<2, j, b[k](j-1)); for t to k do
           b[t]:= wtr(b[t-1]) od: eval(b[0])
        end:
    A:= (n, k)-> g(k)(n):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    wtr[p_] := Module[{b}, b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[p[i], j]*b[n - i*j, i - 1], {j, 0, n/i}]]]; b[#, #]&];
    g[k_] := g[k] = Module[{b, t}, b[0][j_] := If[j < 2, j, b[k][j - 1]]; For[ t = 1, t <= k + 1, t++, b[t] = wtr[b[t - 1]]]; b[0]];
    A[n_, k_] := g[k][n];
    Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jul 10 2018, after Alois P. Heinz *)

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

Views

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 1-4 of 4 results.