A095407 Total number of decimal digits of all distinct prime factors of n.

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 3, 2, 2, 1, 3, 1, 2, 2, 3, 2, 1, 3, 3, 2, 2, 2, 3, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 1, 2, 3, 3, 2, 2, 3, 2, 3, 3, 2, 3, 2, 3, 2, 1, 3, 4, 2, 3, 3, 3, 2, 2, 2, 3, 2, 3, 3, 4, 2, 2, 1, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 2, 2, 3, 2, 3, 4, 3, 3, 3

Offset: 1

Author

Labos Elemer, Jun 21 2004

Keywords

• base
• nonn

Comments

a(n) <= A055642(n) + A001221(n) - 1 since the product of a k digit number and an m digit number has at least k+m-1 digits. - Chai Wah Wu, Nov 03 2019

Examples

			n=22: prime set={2,11}, a[22]=1+2=3.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A055642, A001221.

Programs

Mathematica

Prepend[(Total [ Length[IntegerDigits[#]] & /@ ( #[[1]] & /@ FactorInteger[#])] & /@ Range[2, 105]), 0] (* Zak Seidov, Aug 26 2016 *)

PARI

a(n)=vecsum(apply(p->#Str(p), factor(n)[,1])) \\ Charles R Greathouse IV, Aug 26 2016