On the Subject of Accelerando

"12 B." "Okay, what's next?" "14 C." "Okay, go on." "20 P." "Wait, what was the number?" "4 Z." "No, the last..." "2 G. 19 Q. 6 E." "Slow down!" "7 U. 21 R. 16 W. 18 D..."

The module starts off by displaying a 'GO' button. Upon pressing the 'GO' button, the module will start displaying a set of twenty number-letter pairs. Take note of each number-letter pair. If you press 'GO' again, the same set of number-letter pairs will appear but in a different order. There will always be exactly 20 number-letter pairs.

Now, find the alphabetic position for the letters in each pair, and calculate the differences between the two values of each pair.

Now, reorder the list of differences from least to greatest, remove all but the first of any duplicates, and observe the third, sixth, ninth, and twelfth number in the resulting list.

Press the letter that is next to these numbers.

To submit an answer, press the 'GO' button, and then proceed to press the correct four letters.

If you either press a wrong letter or miss a correct letter, a strike will be incurred. However, the strike will only be incurred after the sequence finishes. Striking will also generate a new set of number-letter pairs.

After successfully pressing the correct four letters, the puzzle will be solved and the module will disarm.