update2: after some thinking, I'm convinced it's ok.

#!perl -w
use strict;
my $end = shift || 40;
my $i = merge_multiple(@ARGV ? @ARGV : (2,3,5));

print $i->(),"\n" for 1 .. $end;

sub merge_multiple {
    my $last = 0;
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    my %vals = map { $_ => $_ } sort { $a <=> $b } @_;
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    my %vals = map { $_ => $_ } @_; 
    sub {
        for (keys %vals) {
            $vals{$_} += $_ if $vals{$_} <= $last;
        }
        my ($r) = sort { $a <=> $b } values %vals;
        $last = $r;
    }
}
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