print OUT "Genome: \n $line\n";
#                  ^^      ^^

##</code><code>##

use strict;
use warnings;

print 'Genome: ';

while (my $line = <DATA>) 
{
    $line =~ s/^[0-9]+//;   # Remove initial digits
    $line =~ s/\s+//g;      # Remove all whitespace (including newlines)

    print $line if $line =~ /[acgt]+/;
}

print "\n";

__DATA__
INPUT

ORIGIN

1 ccctaaaccc taaaccctaa accctaaacc ctaaacccta aaccctaaac cctaaaccct

61 aaaccctaaa ccctaaaccc taaaccctaa accctaaacc ctaaacccta aaccctaaac

121 cctaaaccct aaaccctaaa cgatgcatta ctactcacac gaacgagtga atgaaacaca

##</code><code>##

18:35 >perl 2007_SoPW.pl
Genome: ccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaaccctaaacgatgcattactactcacacgaacgagtgaatgaaacaca

18:35 >