how to find number patterns

Question

9,27,20,60,53,159,152,256,449

Answer 1

There would have been a pattern here if 256 was 456. So I think it may be a mistake in the way the question has been written. The pattern is, starting with 9, multiply by 3 to get the next number, then subtract 7 to get the next; multiply by 3 for the next, subtract 7 for the next; and so on. The pattern would then be: 9, 27, 20, 60, 53, 159, 152, 456, 449.

The next numbers would be: 1347, 1340, 4020, 4013.