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  1. #include <stdio.h>
  2.  
  3. int main(void)
  4. {
  5. //数列a_nは常にa_n>a_(n-1)を満たす
  6. //a_2 = 8
  7. int a_l, a_m, a_n, count;
  8. a_l = 1;
  9. a_m = 2;
  10. count = 0;
  11. for(a_n = 8;a_n<=1000;a_n = 3*a_m + 2*a_l)
  12. {
  13. if(a_n>=100)
  14. {
  15. count++;
  16. }
  17. a_l = a_m;
  18. a_m = a_n;
  19. }
  20. printf("100 <= a_n <= 1000 を与えるnは%d個ある",count);
  21. return 0;
  22. }
  23.  
Success #stdin #stdout 0s 5272KB
stdin
Standard input is empty
stdout
100 <= a_n <= 1000 を与えるnは2個ある