Gcd ← ⊙◌⍢(˜⟜◿|⊃⋅±⊙∘)
# Experimental!
Gcd   ← ∨
NextY ← ⍢(+1|⨬(¬≍0_1=1≡Gcd⊙↙₋₂|1)˜∊⊃⊙∘⊙∘)1 # [a0 a1...an] -> an+1
N     ← 200
⍢(˜⊂NextY|<N⧻)[1 2 3]
⟜↙₃₀        # First 30
▽⟜≡▽2⊞= ⇌⇡N # Plot 200