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 1-5 of 5 results.

A350732 Triangle read by rows: T(n,k) is the number of weakly connected oriented graphs on n labeled nodes with k arcs, n >= 0, k=0..n*(n-1)/2.

Original entry on oeis.org

1, 0, 2, 0, 0, 12, 8, 0, 0, 0, 128, 240, 192, 64, 0, 0, 0, 0, 2000, 7104, 13120, 15360, 11520, 5120, 1024, 0, 0, 0, 0, 0, 41472, 234240, 729600, 1578240, 2531840, 3068928, 2795520, 1863680, 860160, 245760, 32768
Offset: 1

Views

Author

Andrew Howroyd, Jan 11 2022

Keywords

Examples

			Triangle begins:
  [1] 1;
  [2] 0, 2;
  [3] 0, 0, 12,   8;
  [4] 0, 0,  0, 128,  240,  192,    64;
  [5] 0, 0,  0,   0, 2000, 7104, 13120, 15360, 11520, 5120, 1024;
  ...
		

Crossrefs

Row sums are A054941.
The leading diagonal is A097629.
The unlabeled version is A350734.
Cf. A062735 (digraphs), A350731 (strongly connected).

Programs

  • PARI
    row(n)={Vecrev(n!*polcoef(1 + log(sum(k=0, n, (1+2*y)^(k*(k-1)/2)*x^k/k!, O(x*x^n))), n))}
    { for(n=1, 5, print(row(n))) }

A350750 Triangle read by rows: T(n,k) is the number of strongly connected oriented graphs on n unlabeled nodes with k arcs, n >= 1, k = 0..n*(n-1)/2.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 1, 5, 18, 27, 19, 6, 0, 0, 0, 0, 0, 0, 1, 8, 80, 333, 765, 1122, 1049, 622, 217, 35, 0, 0, 0, 0, 0, 0, 0, 1, 12, 221, 1875, 8971, 28449, 63845, 105556, 130935, 122607, 85926, 43868, 15506, 3403, 353
Offset: 1

Views

Author

Andrew Howroyd, Jan 13 2022

Keywords

Examples

			Triangle begins:
  [1] 1;
  [2] 0, 0;
  [3] 0, 0, 0, 1;
  [4] 0, 0, 0, 0, 1, 2, 1;
  [5] 0, 0, 0, 0, 0, 1, 5, 18, 27,  19,   6;
  [6] 0, 0, 0, 0, 0, 0, 1,  8, 80, 333, 765, 1122, 1049, 622, 217, 35;
  ...
		

Crossrefs

Row sums are A350489.
Column sums are A350751.
The labeled version is A350731.
Cf. A057276 (digraphs), A350733, A350734.

Programs

  • PARI
    \\ See PARI link in A350489 for program code.
    { my(A=A350750rows(7)); for(n=1, #A, print(A[n])) }

A350733 Triangle read by rows: T(n,k) is the number of oriented graphs on n unlabeled nodes with k arcs, n >= 0, k = 0..n*(n-1)/2.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 4, 10, 12, 10, 4, 1, 1, 4, 13, 41, 78, 131, 144, 107, 50, 12, 1, 1, 4, 14, 55, 187, 539, 1292, 2500, 3817, 4512, 4112, 2740, 1274, 376, 56, 1, 1, 4, 14, 58, 240, 1009, 3643, 11815, 32538, 76145, 149724, 247329, 340364, 387834, 361450, 271177, 159872, 71320, 22690, 4604, 456
Offset: 0

Views

Author

Andrew Howroyd, Jan 13 2022

Keywords

Examples

			Triangle begins:
  [0] 1;
  [1] 1;
  [2] 1, 1;
  [3] 1, 1, 3,  2;
  [4] 1, 1, 4, 10, 12, 10,   4;
  [5] 1, 1, 4, 13, 41, 78, 131, 144, 107, 50, 12;
  ...
		

Crossrefs

Row sums are A001174.
Cf. A350734.

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))}
    row(n)={my(s=0); forpart(p=n, s+=permcount(p)*edges(p, i->1+2*x^i)); Vecrev(s/n!)}
    { for(n=0, 6, print(row(n))) }

A350914 Triangle read by rows: T(n,k) is the number of unlabeled weakly connected oriented graphs with n arcs and k vertices, k = 1..n+1.

Original entry on oeis.org

1, 0, 1, 0, 0, 3, 0, 0, 2, 8, 0, 0, 0, 12, 27, 0, 0, 0, 10, 68, 91, 0, 0, 0, 4, 127, 395, 350, 0, 0, 0, 0, 144, 1144, 2170, 1376, 0, 0, 0, 0, 107, 2393, 9139, 11934, 5743, 0, 0, 0, 0, 50, 3767, 28606, 67104, 64892, 24635, 0, 0, 0, 0, 12, 4500, 71583, 288331, 468702, 352286, 108968
Offset: 0

Views

Author

Andrew Howroyd, Jan 29 2022

Keywords

Examples

			Triangle begins:
  1;
  0, 1;
  0, 0, 3;
  0, 0, 2,  8;
  0, 0, 0, 12,  27;
  0, 0, 0, 10,  68,   91;
  0, 0, 0,  4, 127,  395,  350;
  0, 0, 0,  0, 144, 1144, 2170, 1376;
  ...
		

Crossrefs

Row sums are A350915.
Column sums are A086345.
Cf. A350734 (transpose), A350789 (digraphs).

Programs

  • PARI
    \\ See A350734 for G, InvEulerMTS.
    T(n)={my(p=InvEulerMTS(sum(i=0, n, G(i, y+O(y^n))*x^i, O(x*x^n)))); vector(n, n, Vec(O(x^n)+polcoef(p,n-1,y)/x, -n))}
    { my(A=T(10)); for(n=1, #A, print(A[n])) }

A350915 Number of weakly connected oriented graphs with n arcs.

Original entry on oeis.org

1, 1, 3, 10, 39, 169, 876, 4834, 29316, 189054, 1294382, 9321232, 70326820, 553433559, 4528840412, 38432156859, 337454775045, 3059843449398, 28602687303185, 275222034228537, 2722343346822614, 27647618196693537, 287970349621911635, 3073082817450997700, 33568654163238906968
Offset: 0

Views

Author

Andrew Howroyd, Jan 29 2022

Keywords

Crossrefs

Row sums of A350914.
Column sums of A350734.

Programs

  • PARI
    \\ See A350734 for G, InvEulerMTS.
    seq(n)=Vec(subst(Pol(InvEulerMTS(sum(i=0, n, G(i, y+O(y^n))*x^i, O(x*x^n)))), x, 1))
Showing 1-5 of 5 results.