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.

A346743 Irregular triangular array read by rows. T(n,k) is the number of matrices in GL_n(F_2) having order k, 1<=k<=2^n-1, n>=1.

Original entry on oeis.org

1, 1, 3, 2, 1, 21, 56, 42, 0, 0, 48, 1, 315, 1232, 3780, 1344, 5040, 5760, 0, 0, 0, 0, 0, 0, 0, 2688, 1, 6975, 75392, 416640, 666624, 1249920, 476160, 624960, 0, 0, 0, 833280, 0, 1428480, 1333248, 0, 0, 0, 0, 0, 952320, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1935360
Offset: 1

Views

Author

Geoffrey Critzer, Jul 31 2021

Keywords

Examples

			  1,
  1,   3,    2,
  1,  21,   56,   42,    0,    0,   48,
  1, 315, 1232, 3780, 1344, 5040, 5760, 0, 0, 0, 0, 0, 0, 0, 2688
		

Crossrefs

Cf. A002884 (row sums), A346019.

Programs

  • Mathematica
    nn = 7; q = 2; b[p_, i_] := Count[p, i];d[p_, i_] := Sum[j b[p, j], {j, 1, i}] + i Sum[b[p, j], {j, i + 1, Total[p]}];aut[deg_, p_] :=Product[Product[q^(d[p, i] deg) - q^((d[p, i] - k) deg), {k, 1, b[p, i]}], {i, 1,Total[p]}]; A001037 =Table[1/n Sum[MoebiusMu[n/d] q^d, {d, Divisors[n]}], {n, 1,nn}]; Table[a = Drop[Transpose[  Table[g[u_, v_, deg_] :=Total[Map[v^Length[#] u^(deg Total[#])/aut[deg, #] &,
      Level[Table[IntegerPartitions[n, {0, n}, Range[Drop[FactorList[z^k - 1, Modulus -> q], 1][[1,2]]]], {n, 0, nn}], {2}]]];degreelist =Map[Exponent[#, z] &, Drop[FactorList[z^k - 1, Modulus -> q], 1][[All, 1]]];Table[Product[q^n - q^i, {i, 0, n - 1}], {n, 0,nn}] CoefficientList[Series[Product[g[u, 1, deg], {deg, degreelist}], {u, 0, nn}],u], {k, 1, 2^nn - 1}]], 1][[n]];Nest[Append[#,   a[[Length[#] + 1]] - Sum[#[[j]], {j, Drop[Divisors[Length[#] + 1], -1]}]] & , {1},2^n - 2], {n, 1, nn}]

Formula

T(n,2^n - 1) = A346019(n).