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