Show the decimal value of a number of 1s appended with a 3 then squared

In an attempt to stave of terminal ennui, Find the first 8 where a(n) is semiprime.

say "$_, {.²}" for (^∞).map({ ( 1 x $_ ~ 3)} ).grep({ .is-prime })[^8]

Output:

3, 9
13, 169
113, 12769
11113, 123498769
111111113, 12345679432098769
11111111113, 123456790165432098769
111111111111111111111113, 12345679012345679012346098765432098765432098769
111111111111111111111111111111111111111111111111111111111111111111111111111111111113, 12345679012345679012345679012345679012345679012345679012345679012345679012345679012765432098765432098765432098765432098765432098765432098765432098765432098765432098769