#include <stdio.h>
int main(void) {
int a,b,c,i=0;
for (a=1,b=2;b <= 1000;){
c =3*b+ 2*a;
a = b;
b = c;
if ((100 <= b) && (b <= 1000)){
i = i +1;
}
}
printf("この数列のうち、100以上から1000以下となるのは%d個ある",i
); return 0;
}
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