Problem 3

How to calculate number of genotypes in genetics problem?
How many different F2 genotypes would you expect in a cross with four heterozygous gene pairs?

I know there is some sort of formula, but I can't find it!


Every gene pair produces three genotypes: AA, Aa and aa
So for four heterozygous gene pairs produce 3^4 = 81
AABBCCDD
AABBCCDd
AABBCCdd
AABBCcDD
...
...
...
AaBbCcDD
AaBbCcDd
AaBbCcdd
...
...
aabbccDd
aabbccdd