Led Strobe Lights (Multi Patterns) Help

Anotherwords, What is a code I can Write that will make this work.....

led1 will Flash;

HIGH 20ms
LOW 50ms
HIGH 20ms
LOW 50ms
HIGH 20ms
LOW 50ms
HIGH 250ms
LOW 20ms

then led2 will do the same
and repeats

??? really confused, I tried many types of code and nothing works for me