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  1. a(n){return(n<2)?0:4*a(n-1)+a(n-2)+2;}
  2.  
  3. #include <stdio.h>
  4.  
  5. int main()
  6. {
  7. 	printf("n\tsum\n");
  8. 	for (int i = 1; i < 10; i++)
  9. 	{
  10. 	  printf("%d\t%d\n", i, a(i));
  11. 	}
  12. 	printf("\n");
  13. 	for (int i = 9; i > 0; i--)
  14. 	{
  15. 	  printf("%d\t%d\n", i, a(i));
  16. 	}
  17. }
  18.  
Success #stdin #stdout 0s 2168KB
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stdin
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Standard input is empty
stdout
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n	sum
1	0
2	2
3	10
4	44
5	188
6	798
7	3382
8	14328
9	60696

9	60696
8	14328
7	3382
6	798
5	188
4	44
3	10
2	2
1	0
https://ideone.com/bbQN0T
language:
C (gcc 8.3)
created:
7 years ago
visibility:
public

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