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1 #include2 #include 3 #define E 0.57721566490153286060651209 4 int main() 5 { 6 double a,x; 7 while (scanf("%lf",&a) != EOF) 8 { 9 10 x = E;11 x *= pow(2,a) - 1;12 printf("%1.12e\n",x);13 }14 return 0 ;15 }