N = 7

[C1] non-units	[C2] #non-units lead to same #solution for	[C3] #solution for = non-units in C1
0	1	7
	C2TC3 = #ways delta can be non-unit	7

Total non-singular EC over Z₇ = 7² - #ways delta can be non-unit (C₂^TC₃) = 42