Having a TTFFTTFF... pattern is quite easy: 

  DB<11> $i = 0; say for grep { $i++ % 4 < 2 } 0..12
0
1
4
5
8
9
12

[download]
And starting at the fourth value in the pattern just means your start at the fourth value of $i: 
  DB<12> $i = 3; say for grep { $i++ % 4 < 2 } 0..12
1
2
5
6
9
10

[download]

In reply to Re: Grep Pattern by Eily
in thread Grep Pattern by GotToBTru

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