one of many possible solutions:
{(1○⍺)>2○⍵} {(⍹ ⍵)/⍨⍵ ⍶ ⍹ ⍵} {⍵*2} {⍵/⍨2|⍵}⍳50 1 9 49 225 361 441 625 1089 1521 1681 2025 2209
Thanks for an APL solution in any case!