APL Hacking: Project Euler Daily (#7)
∇R←PESEVEN;X;N;⎕IO ⎕IO←1⍝ The 10001st prime number.
N←150000 ⋄ X←N⍴1 ⋄ I←2
LOOP:X[I×1↓⍳⌊N÷I]←0 ⋄ I←I+(I↓X)⍳1 ⋄ →(N>I*2)/LOOP
X←X/⍳N ⋄ R←(1↓X)[10001]
∇
∇R←PESEVEN;X;N;⎕IO ⎕IO←1⍝ The 10001st prime number.
N←150000 ⋄ X←N⍴1 ⋄ I←2
LOOP:X[I×1↓⍳⌊N÷I]←0 ⋄ I←I+(I↓X)⍳1 ⋄ →(N>I*2)/LOOP
X←X/⍳N ⋄ R←(1↓X)[10001]
∇