Regular Expressions 101

Explanation
Pro

^start of line

Group 1(\d+)

\d+a digit, repeated at least once

Non-Capturing Group(?: \1){2}

{2}repeats the group contents below exactly 2 times:

the literal (32₁₀ / 40₈ / 20₁₆)

\1the text saved by group 1

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

26 tokens

^(\d+)(?: \1){2}$

New

42 42
42 42 42
42 42 42 42
32 42 42
42 42 32

42 42
42 42 42
42 42 42 42
32 42 42
42 42 32