my $n = ...;
    my $b = ...;

    my @possibles;

    my $p = '1';
    while ($p <= $n) {
        push @possibles, ('1' x $p);
        $p *= $b;
    }

    my ($pat) =
        map qr/$_/,
        join '|',
        @possibles;

    print( "$n: ", ('1' x $n) =~ /^$pat\z/ ?1:0, "\n" );