Problem: mysterious numbers

Code: mysterious+numbers/whio_1771369078

Nibbles version: 0.2 | 0.21 | 0.22 | 0.23 | 0.24 | 0.25 | 1.00

Format: Compact | Simple | +Type | Table | JSON | .nbl (DeBruijn) | .nbl (names)

?, (if/else (lazy list)):[int] 
    / (foldr):[int] 
        ^ (replicate):[int] 
            3 (integer):int 
            + (add):[int] 
                2 (integer):int 
                , (range from 1):[int] 
                    3 (integer):int 
        - (diff):[int] <--arg( B:int A:int ) 
            ;@ (= ints):[int] 
            ^ (replicate):[int] 
                4 (integer):int 
                , (range from 1):[int] 
                    ; (save):int -->let( C:int ) 
                        1 (integer):int 
        `% (split list (keep empties)):[[int]] <--arg( E:int D:[int] ) 
            @ (= D):[int] 
            : (append):[int] 
                $ (= E):int 
                2 (integer):int 
    $ (= F):[int] <--arg( F:[int] ) 
    (implicit arg = C):int