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 1-3 of 3 results.

A346209 Number of n X n matrices over GF(3) with no eigenvalues in GF(3), i.e., neither 0 nor 1 nor 2 is an eigenvalue.

Original entry on oeis.org

1, 0, 18, 3456, 7619508, 149200289280, 26394940582090344, 42062797470468915399168, 603463180651533072058654437264, 77927374189849689541269666899007713280, 90570450400853976077932766909301405665963077152
Offset: 0

Views

Author

Geoffrey Critzer, Jul 10 2021

Keywords

Comments

Equivalently, a(n) is the number of n X n matrices over GF(3) whose characteristic polynomial has no linear factors.

Crossrefs

Programs

  • Mathematica
    nn = 10; q = 3; \[Nu] = Table[1/n Sum[MoebiusMu[n/d] q^d, {d, Divisors[n]}], {n, 1, nn}];Table[Product[q^n - q^i, {i, 0, n - 1}], {n, 0, nn}] CoefficientList[Series[Product[Product[1/(1 - u^d/q^(r d)), {r, 1, \[Infinity]}]^\[Nu][[d]], {d, 2, nn}], {u, 0, nn}], u]

Formula

Sum_{n>=0} a(n)*x^n/A053290(n) = Product_{d>=2} (Product_{r>=1} 1/(1-x^d/3^(r*d)))^A027376(d).

A053071 Number of n X n invertible binary matrices A such that A^5+I is invertible.

Original entry on oeis.org

0, 2, 48, 4480, 2887680, 5373624320, 44196975083520, 1442855588252876800, 188570467779447305011200, 98800579402758985681259724800, 207089099087390763078860569942425600
Offset: 1

Views

Author

Vladeta Jovovic, Mar 18 2000

Keywords

References

  • V. Jovovic, The cycle index polynomials of some classical groups, Belgrade, 1995, unpublished.

Crossrefs

A346384 Triangle read by rows. T(n,k) is the number of invertible n X n matrices over GF(3) such that the dimension of the eigenspace corresponding to the eigenvalue 1 is k, 0 <= k <= n, n >= 0.

Original entry on oeis.org

1, 1, 1, 27, 20, 1, 6291, 4719, 221, 1, 13589289, 10191960, 477750, 2120, 1, 266377183929, 199782888129, 9364822830, 41559870, 19481, 1, 47123189360124723, 35342392020078780, 1656674625945339, 7352106327720, 3446299857, 176540, 1
Offset: 0

Views

Author

Geoffrey Critzer, Jul 14 2021

Keywords

Examples

			             1;
             1,            1;
            27,           20,          1;
          6291,         4719,        221,        1;
      13589289,     10191960,     477750,     2120,     1;
  266377183929, 199782888129, 9364822830, 41559870, 19481, 1;
		

Crossrefs

Cf. A051680 (column k=0), A053290 (row sums).

Programs

  • Mathematica
    nn = 6; q = 3; 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]}]; A027376 = Table[1/n Sum[MoebiusMu[n/d] q^d, {d, Divisors[n]}], {n, 1, nn}];
    g[u_, v_] := Total[Map[v^Length[#] u^Total[#]/aut[1, #] &, Level[Table[IntegerPartitions[n], {n, 0, nn}], {2}]]]; Map[Select[#, # > 0 &] &, Table[Product[q^n - q^i, {i, 0, n - 1}], {n, 0,  nn}] CoefficientList[
        Series[(g[u, v] /. v -> 1)*g[u, v]* Product[Product[1/(1 - (u/q^r)^d), {r, 1, \[Infinity]}]^A027376[[d]], {d, 2, nn}], {u, 0, nn}], {u, v}]] // Grid
Showing 1-3 of 3 results.