OFFSET
1,2
COMMENTS
Trivially, for the four single-digit primes p, a(p)=p.
It's not possible by definition to have a digit product equal to a prime number greater than 10, so a(p)=0 for prime p > 10.
LINKS
Graham Holmes, Table of n, a(n) for n = 1..10000
EXAMPLE
a(4) = 10: 1114, 1122, 1141, 1212, 1221, 1411, 2112, 2121, 2211, 4111.
MAPLE
b:= proc(n, t, i) option remember; `if`(n=1, 1/t!, `if`(i<2, 0,
add(b(n/i^j, t-j, i-1)/j!, j=0..padic[ordp](n, i))))
end:
a:= n-> n!*b(n$2, 9):
seq(a(n), n=1..56); # Alois P. Heinz, Jun 12 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Graham Holmes, Jun 12 2024
STATUS
approved