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.

A304942 Triangle read by rows: T(n,k) is the number of nonisomorphic binary n X n matrices with k 1's per column under row and column permutations.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 5, 11, 5, 1, 1, 7, 35, 35, 7, 1, 1, 11, 132, 410, 132, 11, 1, 1, 15, 471, 6178, 6178, 471, 15, 1, 1, 22, 1806, 122038, 594203, 122038, 1806, 22, 1, 1, 30, 7042, 2921607, 85820809, 85820809, 2921607, 7042, 30, 1
Offset: 0

Views

Author

Andrew Howroyd, May 23 2018

Keywords

Examples

			Triangle begins (n >=0, k >= 0):
  1;
  1,  1;
  1,  2,    1;
  1,  3,    3,      1;
  1,  5,   11,      5,      1;
  1,  7,   35,     35,      7,      1;
  1, 11,  132,    410,    132,     11,    1;
  1, 15,  471,   6178,   6178,    471,   15,  1;
  1, 22, 1806, 122038, 594203, 122038, 1806, 22, 1;
  ...
		

Crossrefs

Columns k=1..5 are A000041, A247417, A247596, A247597, A247598.
Cf. A305027.

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}
    K(q,t,k)={polcoeff(prod(j=1, #q, my(g=gcd(t, q[j])); (1 + x^(q[j]/g) + O(x*x^k))^g), k)}
    Blocks(n,m,k)={my(s=0); forpart(q=m, s+=permcount(q)*polcoeff(exp(sum(t=1, n, K(q,t,k)/t*x^t) + O(x*x^n)), n)); s/m!}
    for(n=0, 10, for(k=0, n, print1(Blocks(n,n,k), ", ")); print)

A247596 Number of nonisomorphic binary n X n matrices with three 1's per column under row and column permutations.

Original entry on oeis.org

1, 5, 35, 410, 6178, 122038, 2921607, 81609320, 2588949454, 91699869557, 3582942335285, 153048366545566, 7096576775166579, 355120233277118103, 19084972486216897560, 1096965038775477639368, 67192642484367187943761, 4372413334294007638726854
Offset: 3

Views

Author

Marko Riedel, Sep 21 2014

Keywords

Crossrefs

Column k=3 of A304942.
A diagonal of A305027.

Programs

  • Maple
    seq(matrix_marks(n,3), n=3..15); # Using the uploaded program to A247417
  • PARI
    \\ See A304942 for Blocks
    a(n) = Blocks(n, n, 3); \\ Andrew Howroyd, May 23 2018

Extensions

Terms a(17) and beyond from Andrew Howroyd, May 23 2018

A247597 Number of nonisomorphic binary n X n matrices with four 1's per column under row and column permutations.

Original entry on oeis.org

1, 7, 132, 6178, 594203, 85820809, 16341829155, 3875736708590, 1112175913348040, 378860991866916370, 151006214911844288232, 69600017255860985666964, 36729204987785981237238642, 22003003913198378660826731007, 14851323097928973689736994569534
Offset: 4

Views

Author

Marko Riedel, Sep 21 2014

Keywords

Crossrefs

Column k=4 of A304942.

Programs

  • Maple
    seq(matrix_marks(n,4), n=3..15); # Using the uploaded program to A247417
  • PARI
    \\ See A304942 for Blocks
    a(n) = Blocks(n, n, 4); \\ Andrew Howroyd, May 24 2018

Extensions

Terms a(16) and beyond from Andrew Howroyd, May 24 2018

A247598 Number of nonisomorphic binary n X n matrices with five 1's per column under row and column permutations.

Original entry on oeis.org

1, 11, 471, 122038, 85820809, 96018336018, 146662126879117, 291352421255114277, 734102568216405642199, 2304488853198195872625924, 8882860158091727486388086786, 41519759838668575020971562079517, 232748666229847254694256869145439898, 1549417862125158239133077344950011140191
Offset: 5

Views

Author

Marko Riedel, Sep 21 2014

Keywords

Crossrefs

Column k=5 of A304942.

Programs

  • Maple
    seq(matrix_marks(n,5), n=3..15); # Using the uploaded program to A247417
  • PARI
    \\ See A304942 for Blocks
    a(n) = Blocks(n, n, 5); \\ Andrew Howroyd, May 24 2018

Extensions

Terms a(16) and beyond from Andrew Howroyd, May 24 2018
Showing 1-4 of 4 results.