A341882 Number of ordered factorizations of n into 6 factors > 1.

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6

Offset

64,33

Links

Alois P. Heinz, Table of n, a(n) for n = 64..20000

Eric Weisstein's World of Mathematics, Ordered Factorization

Formula

Dirichlet g.f.: (zeta(s) - 1)^6.

a(n) = 15 * A000005(n) - 20 * A007425(n) + 15 * A007426(n) - 6 * A061200(n) + A034695(n) - 6 for n > 1.

Maple

b:= proc(n) option remember; series(x*(1+add(b(n/d),
      d=numtheory[divisors](n) minus {1, n})), x, 7)
    end:
a:= n-> coeff(b(n), x, 6):
seq(a(n), n=64..160);  # Alois P. Heinz, Feb 22 2021

Mathematica

b[n_] := b[n] = Series[x*(1 + Sum[b[n/d],
     {d, Divisors[n]~Complement~{1, n}}]), {x, 0, 7}];
a[n_] := Coefficient[b[n], x, 6];
Table[a[n], {n, 64, 160}] (* Jean-François Alcover, Feb 28 2022, after Alois P. Heinz *)

Crossrefs

Column k=6 of A251683.

Cf. A000005, A007425, A007426, A034695, A061200, A070824, A074206, A200221, A341880, A341881.

Sequence in context: A273941 A067483 A186685 * A307382 A339629 A331428

Adjacent sequences: A341879 A341880 A341881 * A341883 A341884 A341885

Keyword

nonn

Author

Ilya Gutkovskiy, Feb 22 2021

Status

approved