#include <stdio.h>
//a{n+1} = -2a{n} + 4, a{0}=2(再帰なし版)
int main(void) {
int n;
int an = 2;
for(int i = 0;i<n;i++){
an = -2*an + 4;
}
printf("数列a%dの値は%d\n", n
, an
);
return 0;
}
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