OFFSET
0,4
EXAMPLE
The a(1) = 1 through a(4) = 14 chains (with n! prepended):
1 2/1 6/1 24/1
6/2/1 24/2/1
6/3/1 24/3/1
24/4/1
24/8/1
24/12/1
24/4/2/1
24/8/2/1
24/8/4/1
24/12/2/1
24/12/3/1
24/12/4/1
24/8/4/2/1
24/12/4/2/1
MATHEMATICA
chnstr[n_]:=If[n==1, 1, Sum[chnstr[d], {d, Select[Most[Divisors[n]], UnsameQ@@Last/@FactorInteger[#]&]}]];
Table[chnstr[n!], {n, 0, 5}]
CROSSREFS
A336571 is the generalization to not just factorial numbers.
A337104 is the version for chains containing n!.
A000005 counts divisors.
A001055 counts factorizations.
A032741 counts proper divisors.
A071625 counts distinct prime multiplicities.
A074206 counts chains of divisors from n to 1.
A130091 lists numbers with distinct prime multiplicities.
A181796 counts divisors with distinct prime multiplicities.
A253249 counts chains of divisors.
A327498 gives the maximum divisor with distinct prime multiplicities.
A336414 counts divisors of n! with distinct prime multiplicities.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Aug 17 2020
STATUS
approved