let k be Nat; for p being Prime st p * p <= k & k < 1369 & not p = 2 & not p = 3 & not p = 5 & not p = 7 & not p = 11 & not p = 13 & not p = 17 & not p = 19 & not p = 23 & not p = 29 holds
p = 31
let p be Prime; ( p * p <= k & k < 1369 & not p = 2 & not p = 3 & not p = 5 & not p = 7 & not p = 11 & not p = 13 & not p = 17 & not p = 19 & not p = 23 & not p = 29 implies p = 31 )
assume
( p * p <= k & k < 1369 )
; ( p = 2 or p = 3 or p = 5 or p = 7 or p = 11 or p = 13 or p = 17 or p = 19 or p = 23 or p = 29 or p = 31 )
then
p * p < 37 * 37
by XXREAL_0:2;
hence
( p = 2 or p = 3 or p = 5 or p = 7 or p = 11 or p = 13 or p = 17 or p = 19 or p = 23 or p = 29 or p = 31 )
by Th21, NAT_4:1; verum