7 lines
149 B
Perl
7 lines
149 B
Perl
use ntheory qw/forprimes znorder/;
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my($t,$z)=(0,0);
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forprimes {
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$z = znorder(10, $_);
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$t++ if defined $z && $z+1 == $_;
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} 8192000;
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print "$t\n";
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