4, 7, 26, 10, 13, 20, 16, ... choose which pair of numbers comes next?

Two patterns alternate here, with every third number following the alternate pattern. In the main series(1st series) 4, 7, 10,13, 16 ..... beginning with 4, 3 is added to each number to arrive at the next. Secondary series (2nd series): 26, 20, ... beginning with 26, 6 is subtracted from each number to arrive at the next. Therefore Next two number is 19(from 1st series), 14(from 2nd series). 19,14