1,2

Motivated by seeking an explanation for A080592. For n >= 2, 1 <= a(n) <= 45. For n >= 1, a(n) <= A095402(n).

Table of n, a(n) for n=1..90.

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).

Join[{0}, Rest[Total[Union[Flatten[IntegerDigits/@Transpose[ FactorInteger[ #]][[1]]]]]&/@Range[90]]] (* Harvey P. Dale, Nov 30 2011 *)

Cf. A095402, A080592, A008472.

Sequence in context: A240858 A035361 A137851 * A095402 A086294 A075860

Adjacent sequences: A141343 A141344 A141345 * A141347 A141348 A141349

base,nonn

Rick L. Shepherd, Jun 26 2008

approved