In a manner similar to twin primes, twin Ramanujan primes may be explored. The task is to determine how many of the first million Ramanujan primes are twins.

Related Task
 Twin primes
use strict;
use warnings;
use ntheory <ramanujan_primes nth_ramanujan_prime>;
 
sub comma { reverse ((reverse shift) =~ s/(.{3})/$1,/gr) =~ s/^,//r }
 
my $rp = ramanujan_primes nth_ramanujan_prime 1_000_000;
for my $limit (1e5, 1e6) {
    printf "The %sth Ramanujan prime is %s\n", comma($limit), comma $rp->[$limit-1];
    printf  "There are %s twins in the first %s Ramanujan primes.\n\n",
        comma( scalar grep { $rp->[$_+1] == $rp->[$_]+2 } 0 .. $limit-2 ), comma $limit;
}