sub line {
    my @a1 = @_;
    my @b;
    push @b, " 1";
    push @b, $a1[$_] + $a1[ $_ - 1 ] foreach ( 1 .. $#a1 + 1 );
    return @b;
}

my @b = qw(1 1);
my $s = 100;
print " " x ($s), " 1\n";

foreach ( 2 .. shift ) {
    my $l = join " ", @b;
    print " " x ( $s - ( length $l ) / 2 ), "$l\n";
    @b = line(@b);
    shift @b;
}
[download]