use strict;
use warnings;

my $param_a = 1.5;
my $param_b = 6;

my @array = ( 1 .. 100 );

sub invK {
    my ($F, $Ka, $Kb) = @_;
    return ( 1 - ( 1 - $F )**( 1 / $Kb ) )**( 1 / $Ka );
}

for ( 1 .. 20 ) {
    my $pick = int( invK( rand(), $param_a, $param_b ) * @array );
    print "$pick\n";
}