Lm1:
for n being Element of NAT st 1 < n & n < 5 & n is prime & not n = 2 holds
n = 3
Lm2:
( not 6 is prime & not 8 is prime & not 9 is prime & not 10 is prime & not 12 is prime & not 14 is prime & not 15 is prime & not 16 is prime & not 18 is prime & not 20 is prime & not 21 is prime & not 22 is prime & not 24 is prime & not 25 is prime & not 26 is prime & not 27 is prime & not 28 is prime )
Lm3:
for n being Element of NAT st 1 < n & n < 29 & n is prime & not n = 2 & not n = 3 & not n = 5 & not n = 7 & not n = 11 & not n = 13 & not n = 17 & not n = 19 holds
n = 23
Lm4:
for k being Element of NAT st k < 841 holds
for n being Element of NAT st 1 < n & n * n <= k & n is prime & not n = 2 & not n = 3 & not n = 5 & not n = 7 & not n = 11 & not n = 13 & not n = 17 & not n = 19 holds
n = 23