

Definition

A factorion is a natural number that equals the sum of the factorials of its digits.



Example
 
145   is a factorion in base 10 because:


          1! + 4! + 5!   =   1 + 24 + 120   =   145 





It can be shown (see talk page) that no factorion in base 10 can exceed   1,499,999.



Task

Write a program in your language to demonstrate, by calculating and printing out the factorions, that:

   There are   3   factorions in base   9
   There are   4   factorions in base 10
   There are   5   factorions in base 11 
   There are   2   factorions in base 12     (up to the same upper bound as for base 10)


See also

 Wikipedia article
 OEIS:A014080 - Factorions in base 10
 OEIS:A193163 - Factorions in base n


fact = [1] # cache factorials from 0 to 11
for n in range(1, 12):
    fact.append(fact[n-1] * n)
 
for b in range(9, 12+1):
    print(f"The factorions for base {b} are:")
    for i in range(1, 1500000):
        fact_sum = 0
        j = i
        while j > 0:
            d = j % b
            fact_sum += fact[d]
            j = j//b
        if fact_sum == i:
            print(i, end=" ")
    print("\n")
 