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  1. <?php
  2. function ulam_diag($N)
  3. {
  4. 	$result = array();
  5.  
  6. 	if ($N % 2 == 0) {
  7. 		for ($n = 0; $n < $N / 2; $n++) {
  8. 			$result[] = 4*$n*$n + 2*$n + 1;
  9. 			$result[] = 4*$n*$n + 4*$n + 2;
  10. 			$result[] = 4*$n*$n + 8*$n + 4;
  11. 			$result[] = 4*$n*$n + 6*$n + 3;
  12. 		}
  13. 	} else {
  14. 		$result[] = 1;
  15. 		for ($n = 1; $n <= ($N - 1) / 2; $n++) {
  16. 			$result[] = 4*$n*$n + 2*$n + 1;
  17. 			$result[] = 4*$n*$n + 4*$n + 1;
  18. 			$result[] = 4*$n*$n + 1;
  19. 			$result[] = 4*$n*$n - 2*$n + 1;			
  20. 		}
  21. 	}
  22.  
  23. 	sort($result);
  24. 	return $result;
  25. }
  26.  
  27. print_r(ulam_diag(4));
  28. print_r(ulam_diag(3));
  29. ?>
Success #stdin #stdout 0.02s 52472KB
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stdin
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Standard input is empty
stdout
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Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 7
    [5] => 10
    [6] => 13
    [7] => 16
)
Array
(
    [0] => 1
    [1] => 3
    [2] => 5
    [3] => 7
    [4] => 9
)
https://ideone.com/F9jaC0
language:
PHP (php 7.3.5)
created:
8 years ago
visibility:
public

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