#! perl -slw
use strict;

sub fact{
    my $n = shift;
    my $f = $n; $f *= $n while --$n;
    return $f;
}

sub nCr{
    my( $n, $r ) = @_;
    return fact( $n ) / ( fact( $r ) * fact( $n - $r ) );
}

sub NwithM {
    my $f = 4-1;
    my( $L, $M ) = @_;
    my $T = 1;
    for my $m ( 1 .. $M ) {
        $T += nCr( $L, $m ) * $f**$m;
    }
    return $T;
}


print "8 with $_ mismatch(es): ", NwithM( 8, $_ ) for 1 .. 4;
print "9 with $_ mismatch(es): ", NwithM( 9, $_ ) for 1 .. 4;


##</code><code>##

C:\test\humanGenome>fuzzyDNAcalc.pl
8 with 1 mismatch(es): 25
8 with 2 mismatch(es): 277
8 with 3 mismatch(es): 1789
8 with 4 mismatch(es): 7459
9 with 1 mismatch(es): 28
9 with 2 mismatch(es): 352
9 with 3 mismatch(es): 2620
9 with 4 mismatch(es): 12826