pn  ← {1≥⍵:0≤⍵ ⋄ -/+⌿∇¨rec ⍵}
   pnc ← {1≥⍵:1 ⋄ 1++/∇¨,rec ⍵}    ⍝ # function calls

   pnc¨ ⍳15
1 1 5 9 17 29 49 87 149 261 451 781 1351 2333 4041 
   pnc M¨ ⍳15
1 1 5 9 17 29 49 87 149 261 451 781 1351 2333 4041

   pnc M¨ 30 200
2.59912E7 7.5715E47
   ⊢ s ← 45 × ÷⍨/ pnc M¨ 30 200    ⍝ # of seconds
1.3109E42
   s ÷ ×/ 365.2425 24 60 60        ⍝ # of years
4.15407E34