how do I use the for correctly?

Question

I’m doing an EP activity and he asked me for it in the image, but I got stuck in the sequence part, because, like the sequence is the top numbers is a sequence growing from 1 to infinity, and underneath are potentials of 2, i was wondering how can I make the 2 powers without the Math library, tried a test medium code, I also thought to put the value of the for in some incognita and use it to multiply the equation, but I do not know tbm how to store the value of for but nor scrolls, so to half lost.

#include "stdio.h"
int main(void) {
  int t,i=0;
  float p,QuadNum;

  // seleção inicial 
  printf("digite um numero ");
  scanf("%d",&t);
  for( i=0;i<=t;i++){
QuadNum=i;
  }
  p= (1*2*3*4*5)/(QuadNum*i);
  printf(" o valor é  %f =",p);
  return 0;
}

Answer 1

Just multiply the denominator by 2.

See that there is a pattern:

• the first term is 1 divided by 2
• the second term is 2 divided by 4
• the third term is 3 divided by 8
• ...

That is, with each new term, the numerator increases by 1, and the denominator doubles in value.

So just do it:

float p = 1, denominador = 1;
int qtd;
printf("Digite a quantidade de termos:");
scanf("%d", &qtd);
for (int i = 1; i <= qtd; i++) {
    denominador *= 2;
    p *= i / denominador;
}
printf("O valor é: %f", p);

The numerator is controlled by for, 'cause if I have n terms, it varies from 1 to n (and that’s what the for makes, goes from 1 until the amount of terms informed).

The denominator starts at 1 and each iteration doubles (multiplied by 2).

Having the numerator and denominator, simply divide one by the other and multiply to the current value of p.