#APL(NARS) 35 chars, 70 bytes

{⍵=1:0⋄k-⍨+/+/¨{w=⍵⊃v}¨⍳k←≢v←∪w←π⍵}

the function π find the factorization in prime of its argument; there is few to say it seems clear, but for me does more operations (from factorization) than the minimum...the range of count characters is out golfing languages because it seems too much count, but less than not golfing languages... test:

  f←{⍵=1:0⋄k-⍨+/+/¨{w=⍵⊃v}¨⍳k←≢v←∪w←π⍵}
  f¨1..15
0 0 0 1 0 0 0 2 1 0 0 1 0 0 0 

APL(NARS) 35 chars, 70 bytes

{⍵=1:0⋄k-⍨+/+/¨{w=⍵⊃v}¨⍳k←≢v←∪w←π⍵}

the function π find the factorization in prime of its argument; there is few to say it seems clear, but for me does more operations (from factorization) than the minimum...the range of count characters is out golfing languages because it seems too much count, but less than not golfing languages... test:

  f←{⍵=1:0⋄k-⍨+/+/¨{w=⍵⊃v}¨⍳k←≢v←∪w←π⍵}
  f¨1..15
0 0 0 1 0 0 0 2 1 0 0 1 0 0 0