#!/usr/bin/perl

my($i) = 0;
my(%kp) = (1 => '1', 2 => 'abc', 3 => 'def',
           4 => 'ghi', 5 => 'jkl', 6 => 'mno',
           7 => 'pqrs', 8 => 'tuv', 9 => 'wxyz',
           0 => '0');

rec('', split(//, '4265274'));
# 1945

sub rec {
    my($str, @rest) = @_;
    if (!@rest) {
        print $i++, ": $str\n";
    } else {
        my($first) = shift(@rest);
        my(@choices) = split(//, $kp{$first});

        foreach (@choices) {
            rec("$str$_", @rest);
        }
    }    
}
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