5,4,10,9,15,14,20

What is your question?

-1 +6 -1 +6 -1 +6

so
20-1 = 19
19+6 = 25
25-1 = 24
24+6 = 30 etc

It seems like you have provided a sequence of numbers: 5, 4, 10, 9, 15, 14, 20. It's unclear what you would like to know about this sequence. Do you want to find the pattern or the next number in the sequence? Please provide more information so that I can assist you better.