Help for this page
while( <DATA> ) { s[\s(\d+)\d\K\s(?=(\d+)\d\s)]{ ... }ge; print; }
1051 1061 1071 1081 1091 1101 1111 1121 1131 11151 11161 11171 11181 11191 11201 11211 11221 11231 123451 123461 123471 123481 123491 123501 123511 123531