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  1. #include <stdio.h>
  2. //a{n} = -6a{n-1} -9a{n-2}, a{1}=1, a{2}=2(再帰あり版)
  3. int rec(int n){
  4. 	int c;
  5. 	if(n==1){
  6. 		return 1;
  7. 	}
  8. 	else if(n==2){
  9. 		return 2;
  10. 	}
  11. 	else{
  12. 		c++;
  13. 		return  -6*rec(n-1)-9*rec(n-2);
  14. 	}
  15.     printf("%d",c);
  16. }
  17.  
  18. int main(void) {
  19.     int n = 2;
  20.     printf("数列a%dの値は%d\n", n, rec(n));
  21. 	return 0;
  22. }
  23.  
  24.  
Success #stdin #stdout 0s 5288KB
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Standard input is empty
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数列a2の値は2
https://ideone.com/UUBvAW
language:
C (gcc 8.3)
created:
2 days ago
visibility:
public

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