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  1. #include <stdio.h>
  2. //練習問題G
  3.  
  4. int func(int n){
  5.     int a, b=2, c=1;
  6.     int i;
  7.  
  8. if (n == 1) {
  9.         return c;  // a1 = 1
  10.     } else if (n == 2) {
  11.         return b;  // a2 = 2
  12.     } else {
  13.         // 再帰を使って an = -2*a_{n-1} + 2*a_{n-2}
  14.         return -2 * func(n - 1) + 2 * func(n - 2);
  15.     }
  16. }
  17.  
  18. int main(void) {
  19. 	int n = 3;
  20.     printf("数列anについて, n=%dのときの値は%d\n", n, func(n));
  21. 	return 0;
  22. }
  23.  
Success #stdin #stdout 0.01s 5284KB
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数列anについて, n=3のときの値は-2
https://ideone.com/HBRfHv
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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