A091058 Number of n X n matrices over symbol set {1,...,n} equivalent under any permutation of row, columns or the symbol set.

1, 1, 5, 139, 332034, 173636442196, 27652322898323351716, 2006943506669869627232430791792, 95763314593596534914617136274432901605313744, 4114852471732264714685900791520508800628430894815984377778000

Offset: 0

Author

Christian G. Bower, Dec 17 2003

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..14
• C. G. Bower, Explanation of A091057-A091062
• Index to number of inequivalent matrices modulo permutation of rows and columns

Crossrefs

Cf. A091057, A091059, A091060, A091061, A091062.

Main diagonal of A242095.

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];
Table[Print[n, " ", a[n]]; a[n], {n, 0, 12}] (* Jean-François Alcover, May 29 2023, after Alois P. Heinz in A242095 *)

Sage

Pol. = InfinitePolynomialRing(QQ)
@cached_function
def Z(n):
    if n == 0: return Pol.one()
    return sum(x[k]*Z(n-k) for k in (1..n))/n
@cached_function
def monprod(M):
    p = Pol.one()
    V = [m.variables() for m in M]
    T = cartesian_product(V)
    for t in T:
        r = [Pol.varname_key(str(u))[1] for u in t]
        j = [Pol(M[u[0]]).degree(u[1]) for u in enumerate(t)]
        lcm_r = lcm(r)
        p *= x[lcm_r]^(prod(r)/lcm_r*prod(j))
    return p
@cached_function
def pol_isotop(n,k):
    P = Z(n)
    p = Pol.zero()
    coeffs = P.coefficients()
    mons = P.monomials()
    C = cartesian_product(k*[mons])
    Csorted = [tuple(sorted(u)) for u in C]
    Cset = set(Csorted)
    for c in Cset:
        p += Csorted.count(c)*prod([coeffs[mons.index(u)] for u in c])*monprod(c)
    return p
@cached_function
def rule_sub(r,m):
    D = 0
    for d in divisors(r):
        try: D += d*m.degrees()[-d-1]
        except: break
    return D
def a(n,k=2):
    P = Z(n)
    coeffs = P.coefficients()
    Q = pol_isotop(n,k)
    inds = [Pol.varname_key(str(u))[1] for u in Q.variables()]
    p = 0
    for mon in enumerate(P.monomials()):
        m = Pol(mon[1])
        p += coeffs[mon[0]]*Q.subs({x[i]:rule_sub(i,m) for i in inds})
    return p
# Philip Turecek, Jun 17 2023

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} (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)).

a(n) asymptotic to n^(n^2)/(n!^3) = A002489(n)/(A000142(n)^3).

Extensions

a(9) from Alois P. Heinz, Aug 14 2014