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.

A246106 Number A(n,k) of inequivalent n X n matrices with entries from [k], where equivalence means permutations of rows or columns; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 7, 1, 0, 1, 4, 27, 36, 1, 0, 1, 5, 76, 738, 317, 1, 0, 1, 6, 175, 8240, 90492, 5624, 1, 0, 1, 7, 351, 57675, 7880456, 64796982, 251610, 1, 0, 1, 8, 637, 289716, 270656150, 79846389608, 302752867740, 33642660, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 13 2014

Keywords

Examples

			Square array A(n,k) begins:
  1, 1,    1,        1,           1,              1, ...
  0, 1,    2,        3,           4,              5, ...
  0, 1,    7,       27,          76,            175, ...
  0, 1,   36,      738,        8240,          57675, ...
  0, 1,  317,    90492,     7880456,      270656150, ...
  0, 1, 5624, 64796982, 79846389608, 20834113243925, ...
		

Crossrefs

Main diagonal gives A246107.
A028657, A242106, A353585 are related tables.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, [[]],
          `if`(i<1, [], [b(n, i-1)[], seq(map(p->[p[], [i, j]],
           b(n-i*j, i-1))[], j=1..n/i)]))
        end:
    A:= proc(n, k) option remember; add(add(k^add(add(i[2]*j[2]*
          igcd(i[1], j[1]), j=t), i=s) /mul(i[1]^i[2]*i[2]!, i=s)
          /mul(i[1]^i[2]*i[2]!, i=t), t=b(n$2)), s=b(n$2))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • PARI
    A246106(n,k)=A353585(k,n,n) \\ M. F. Hasler, May 01 2022

Formula

A(n,k) = Sum_{i=0..k} C(k,i) * A256069(n,i).
A(n,k) = Sum_{p,q in P(n)} k^Sum_{i in p, j in q} gcd(i, j) / (N(p)*N(q)) where N(p) = Product_{distinct parts x in p} x^m(x)*m(x)!, m(x) = multiplicity of x in p. - M. F. Hasler, Apr 30 2022 [corrected by Anders Kaseorg, Oct 04 2024]

A242095 Number A(n,k) of inequivalent n X n matrices with entries from [k], where equivalence means permutations of rows or columns or the symbol set; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 5, 1, 0, 1, 1, 8, 18, 1, 0, 1, 1, 9, 139, 173, 1, 0, 1, 1, 9, 408, 15412, 2812, 1, 0, 1, 1, 9, 649, 332034, 10805764, 126446, 1, 0, 1, 1, 9, 749, 2283123, 3327329224, 50459685390, 16821330, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 14 2014

Keywords

Comments

A(n,k) = A(n,k+1) for k >= n^2.

Examples

			A(2,2) = 5:
  [1 1]  [2 1]  [2 2]  [2 1]  [2 1]
  [1 1], [1 1], [1 1], [2 1], [1 2].
Square array A(n,k) begins:
  1, 1,    1,        1,          1,            1, ...
  0, 1,    1,        1,          1,            1, ...
  0, 1,    5,        8,          9,            9, ...
  0, 1,   18,      139,        408,          649, ...
  0, 1,  173,    15412,     332034,      2283123, ...
  0, 1, 2812, 10805764, 3327329224, 173636442196, ...
		

Crossrefs

Main diagonal gives A091058.
A(n,n^2) gives A091057.

Programs

  • Maple
    with(numtheory):
    b:= proc(n, i) option remember; `if`(n=0, {0}, `if`(i<1, {},
          {seq(map(p-> p+j*x^i, b(n-i*j, i-1) )[], j=0..n/i)}))
        end:
    A:= proc(n, k) option remember; add(add(add(mul(mul(add(d*
          coeff(u, x, d), d=divisors(ilcm(i, j)))^(igcd(i, j)*
          coeff(s, x, i)*coeff(t, x, j)), j=1..degree(t)),
          i=1..degree(s))/mul(i^coeff(u, x, i)*coeff(u, x, i)!,
          i=1..degree(u))/mul(i^coeff(t, x, i)*coeff(t, x, i)!,
          i=1..degree(t))/mul(i^coeff(s, x, i)*coeff(s, x, i)!,
          i=1..degree(s)), u=b(k$2)), t=b(n$2)), s=b(n$2))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    b[n_, i_] := b[n, i] = If[n==0, {0}, If[i<1, {}, Flatten@Table[Map[ Function[p, p + j*x^i], b[n - i*j, i - 1]], {j, 0, n/i}]]];
    A[n_, k_] := A[n, k] = Sum[Sum[Sum[Product[Product[With[{g = GCD[i, j]* Coefficient[s, x, i]*Coefficient[t, x, j]}, If[g == 0, 1, Sum[d* Coefficient[u, x, d], {d, Divisors[LCM[i, j]]}]^g]], {j, Exponent[t, x]} ],
    {i, Exponent[s, x]}]/Product[i^Coefficient[u, x, i]*Coefficient[u, x, i]!,
    {i, Exponent[u, x]}]/Product[i^Coefficient[t, x, i]*Coefficient[t, x, i]!,
    {i, Exponent[t, x]}]/Product[i^Coefficient[s, x, i]*Coefficient[s, x, i]!,
    {i, Exponent[s, x]}], {u, b[k, k]}], {t, b[n, n]}], {s, b[n, n]}];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Feb 21 2016, after Alois P. Heinz, updated Jan 01 2021 *)

A091057 Number of n X n matrices over symbol set {1,...,n^2} equivalent under any permutation of row, columns or the symbol set.

Original entry on oeis.org

1, 1, 9, 777, 18500104, 322286625959257, 7368376339801908226685191, 422262377369187686156418513093399998333, 105882936532098986759153041871810253870024776751177723954
Offset: 0

Views

Author

Christian G. Bower, Dec 17 2003

Keywords

Crossrefs

Row sums of A242106.

Programs

  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, {0}, If[i < 1, {}, Flatten @ Table[Map[Function[p, p + j*x^i], b[n - i*j, i - 1]], {j, 0, n/i}]]];
    A242095[n_, k_] := A242095[n, k] = With[{co = Coefficient, ex = Exponent}, Sum[Sum[Sum[Product[Product[With[{g = GCD[i, j]*co[s, x, i]*co[t, x, j]}, If[g == 0, 1, Sum[d*co[u, x, d], {d, Divisors[LCM[i, j]]}]^g]], {j, ex[t, x]}], {i, ex[s, x]}]/Product[i^co[u, x, i]*co[u, x, i]!, {i, ex[u, x]}]/Product[i^co[t, x, i]*co[t, x, i]!, {i, ex[t, x]}]/Product[i^co[s, x, i]*co[s, x, i]!, {i, ex[s, x]}], {u, b[k, k]}], {t, b[n, n]}], {s, b[n, n]}]];
    a[n_] := A242095[n, n^2];
    Table[Print[n, " ", a[n]]; a[n], {n, 0, 6}] (* Jean-François Alcover, May 29 2023, after Alois P. Heinz in A242095 *)

Formula

a(n) = Sum_{1*s_1+2*s_2+...=n, 1*t_1+2*t_2+...=n, 1*u_1+2*u_2+...=n^2} (fixA[s_1, s_2, ...; t_1, t_2, ...; u_1, u_2, ...]/ (1^s_1*s_1!*2^s_2*s_2!*...*1^t_1*t_1!*2^t_2*t_2!*...*1^u_1*u_1!*2^u_2*u_2!*...)) where fixA[...] = Product_{i,j>=1} ((Sum_{d|lcm(i, j)} (d*u_d))^(gcd(i, j)*s_i*t_j)). - corrected by Max Alekseyev, Jun 03 2023

Extensions

a(7), a(8) from Max Alekseyev, Feb 09 2010

A360664 Number of inequivalent n X n matrices using exactly n different symbols, where equivalence means permutations of rows or columns or the symbol set.

Original entry on oeis.org

1, 1, 4, 121, 316622, 170309112972, 27417944542834007012, 1999576637456562016308833727820, 95614444589289128555388037722252407519896044, 4112190260012069813083100063825969898935642267505877920574871
Offset: 0

Views

Author

Alois P. Heinz, Feb 15 2023

Keywords

Examples

			a(2) = 4:
  [1 0]  [1 1]  [1 0]  [1 0]
  [0 0], [0 0], [1 0], [0 1].
		

Crossrefs

Main diagonal of A242106.

Formula

a(n) = A242106(n,n).
Showing 1-4 of 4 results.