OFFSET
1,2
COMMENTS
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..10000
EXAMPLE
a(44) = 3 as 44 = 2^2 * 11 and the sum of the distinct digits of the prime factors is 1 + 2 (whereas A095402(44) = 4 = 1 + 1 + 2).
MATHEMATICA
Join[{0}, Rest[Total[Union[Flatten[IntegerDigits/@Transpose[ FactorInteger[ #]][[1]]]]]&/@Range[90]]] (* Harvey P. Dale, Nov 30 2011 *)
PROG
(Python)
from sympy import factorint
def a(n):
s = set()
for p in factorint(n): s |= set(str(p))
return sum(map(int, s))
print([a(n) for n in range(1, 91)]) # Michael S. Branicky, Dec 12 2023
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Rick L. Shepherd, Jun 26 2008
STATUS
approved