How many types of genotypes of ${\mathrm{F}}_2$ progeny of Mendelian dihybrid cross are neither seen in ${\mathrm{F}}_1$ generation nor in parental generation of the cross? 

The genotypes of ${\mathrm{F}}_2$ generation seen neither in P generation nor in ${\mathrm{F}}_1$ generation are Rr YY, RR Yy, RR yy, rr YY, rrYy and Rr yy. The genotype RrYy is seen in ${\mathrm{F}}_1$ and RRYY and rryy are seen in Parental generation.