cp's OEIS Frontend

A141346 Sum of the distinct digits of the prime factors of n.

%I A141346 #9 Dec 12 2023 17:57:59
%S A141346 0,2,3,2,5,5,7,2,3,7,1,5,4,9,8,2,8,5,10,7,10,3,5,5,5,6,3,9,11,10,4,2,
%T A141346 4,10,12,5,10,12,4,7,5,12,7,3,8,5,11,5,7,7,11,6,8,5,6,9,13,11,14,10,7,
%U A141346 6,10,2,9,6,13,10,5,14,8,5,10,12,8,12,8,6,16,7,3,7,11,12,13,9,14,3,17,10
%N A141346 Sum of the distinct digits of the prime factors of n.
%C A141346 Motivated by seeking an explanation for A080592. For n >= 2, 1 <= a(n) <= 45. For n >= 1, a(n) <= A095402(n).
%H A141346 Michael S. Branicky, <a href="/A141346/b141346.txt">Table of n, a(n) for n = 1..10000</a>
%e A141346 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).
%t A141346 Join[{0},Rest[Total[Union[Flatten[IntegerDigits/@Transpose[ FactorInteger[ #]][[1]]]]]&/@Range[90]]] (* _Harvey P. Dale_, Nov 30 2011 *)
%o A141346 (Python)
%o A141346 from sympy import factorint
%o A141346 def a(n):
%o A141346     s = set()
%o A141346     for p in factorint(n): s |= set(str(p))
%o A141346     return sum(map(int, s))
%o A141346 print([a(n) for n in range(1, 91)]) # _Michael S. Branicky_, Dec 12 2023
%Y A141346 Cf. A095402, A080592, A008472.
%K A141346 base,nonn
%O A141346 1,2
%A A141346 _Rick L. Shepherd_, Jun 26 2008