Hofstadter Figure-Figure sequences

my %r = 1 => 1;
my %s = 1 => 2;

sub ffr ($n) { %r{$n} //= ffr($n - 1) + ffs($n - 1) }
sub ffs ($n) { %s{$n} //= (grep none(map &ffr, 1..$n), max(%s.values)+1..*)[0] }

my @ffr = map &ffr, 1..*;
my @ffs = map &ffs, 1..*;

say @ffr[^10];
say "Rawks!" if 1...1000 eqv sort |@ffr[^40], |@ffs[^960];

Output:

1 3 7 12 18 26 35 45 56 69
Rawks!