Crossnumbers not attained for:

p=3 and q=5
p=3 and q=7
p=3 and q=11
p=3 and q=13
p=3 and q=17
p=3 and q=19
p=3 and q=23

p=5 and q=7
p=5 and q=11
p=5 and q=13

p=7 and q=11