OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
MAPLE
a:= proc(n) option remember; `if`(n=1, 1, min(ithprime(n),
seq(ithprime(d)*a(n/d), d=numtheory[divisors](n) minus {1, n})))
end:
seq(a(n), n=1..60); # Alois P. Heinz, Sep 05 2018
MATHEMATICA
facs[n_]:=If[n<=1, {{}}, Join@@Table[(Prepend[#1, d]&)/@Select[facs[n/d], Min@@#1>=d&], {d, Rest[Divisors[n]]}]];
Table[Min[Times@@Prime/@#&/@facs[n]], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 05 2018
STATUS
approved