QAR, RAS, SAT, TAU, _____
In this series, the third letter is repeated as the first letter of the next segment.
The middle letter, A, remains static.
The third letters are in alphabetical order, beginning with R.
DEF, DEF2, DE2F2, _____, D2E2F3
In this series, the letters remain the same: DEF.
The subscript numbers follow this series: 111, 112, 122, 222, 223, 233, 333, ...
Type1
