My very simple solution

Maybe too simple?

main.c

[code]#include <stdio.h>

int main(int argc, const char * argv[])

unsigned long a = 0;

for (int i = 0; i < 32; i++) {
    a++;
    a = a << 2;
}

a++;

printf("%lu\n", a);

return 0;

}
[/code]

It could be simpler. Start with 1 since we want the odd number. In the loop, shift left twice to get 100, then add 1 to get 101. Repeat. 10100, 10101. etc.

[code]#include <stdio.h>

int main(int argc, const char * argv[])
{
uint64_t big = 1;
for (int i = 0; i < 64; i++) {
big = big << 2;
big = big + 1;
}
printf(“The big number is %llu\n”, big);

return 0;

}[/code]