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  1. #include <stdio.h>
  2. // a[n] = -6a[n-1] - 9a[n-2], a[1]=1, a[2]=2 (再帰版)
  3.  
  4. int rec(int n){
  5.     if (n == 1){
  6.         return 1;
  7.     }
  8.     else if (n == 2){
  9.         return 2;
  10.     }
  11.     else{
  12.         return -6 * rec(n - 1) - 9 * rec(n - 2);
  13.     }
  14. }
  15.  
  16. int main(void){
  17.     int n = 4;
  18.     printf("数列a%dの値は%d\n", n, rec(n));
  19.     return 0;
  20. }
  21.  
Success #stdin #stdout 0s 5324KB
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Standard input is empty
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数列a4の値は108
https://ideone.com/6e8Amb
language:
C (gcc 8.3)
created:
3 days ago
visibility:
public

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