31 lines
501 B
PHP
31 lines
501 B
PHP
<?php
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// Tau number
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// return the Tau (number of divisors) of $n
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function tau(int $n): int {
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if ($n < 3) {
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$t = $n;
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} else {
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$t = 2;
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$limit = intdiv($n + 1, 2);
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for ($i = 2; $i <= $limit; $i++)
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if ($n % $i == 0)
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$t++;
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}
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return $t;
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}
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echo 'First 100 Tau numbers:'.PHP_EOL;
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$c = 0;
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$i = 1;
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while ($c < 100) {
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if ($i % tau($i) == 0) {
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echo str_pad($i, 5, ' ', STR_PAD_LEFT);
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$c++;
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if ($c % 10 == 0)
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echo PHP_EOL;
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}
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$i++;
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}
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echo PHP_EOL;
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?>
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