# Thread: Finding expressions for 4, 8, 32 ???

1. ## Finding expressions for 4, 8, 32 ???

Finding expressions for sequences
example: 2,4, 8, 16, 32 ...is 2^n
where n= rank
example: 3, 9, 27, 81 ...is 3^n

soo what is the expression for 4, 8, 32
you can express it in form of 2 to a certain power
such that it is: 2^2 , 2^3, 2^5
i tried 2^2n-1, it works for the 2nd and 3rd value but not the 1st ???

OR it can be noticed that the powers are prime numbers
so is the expression 2^p(n)

ANY ideas????

2. Yes, it seems that it is 2^nth prime.
2^2=4
2^3=8
2^5=32

Therefore the next would be 2^7=128, 2^11=2048...

3. Originally Posted by GoneCrazy
Finding expressions for sequences
...

soo what is the expression for 4, 8, 32
you can express it in form of 2 to a certain power
such that it is: 2^2 , 2^3, 2^5
i tried 2^2n-1, it works for the 2nd and 3rd value but not the 1st ???

OR it can be noticed that the powers are prime numbers
so is the expression 2^p(n)

ANY ideas????
$2^2, 2^3, 2^{2+3}, 2^{3+5}, 2^{5+8}, ...$