4057 = (2 * 2028) + 1 ;
hence not 2 divides 4057 by NAT_4:9; :: thesis:
4057 = (3 * 1352) + 1 ;
hence not 3 divides 4057 by NAT_4:9; :: thesis:
4057 = (5 * 811) + 2 ;
hence not 5 divides 4057 by NAT_4:9; :: thesis:
4057 = (7 * 579) + 4 ;
hence not 7 divides 4057 by NAT_4:9; :: thesis:
4057 = (11 * 368) + 9 ;
hence not 11 divides 4057 by NAT_4:9; :: thesis:
4057 = (13 * 312) + 1 ;
hence not 13 divides 4057 by NAT_4:9; :: thesis:
4057 = (17 * 238) + 11 ;
hence not 17 divides 4057 by NAT_4:9; :: thesis:
4057 = (19 * 213) + 10 ;
hence not 19 divides 4057 by NAT_4:9; :: thesis:
4057 = (23 * 176) + 9 ;
hence not 23 divides 4057 by NAT_4:9; :: thesis:
4057 = (29 * 139) + 26 ;
hence not 29 divides 4057 by NAT_4:9; :: thesis:
4057 = (31 * 130) + 27 ;
hence not 31 divides 4057 by NAT_4:9; :: thesis:
4057 = (37 * 109) + 24 ;
hence not 37 divides 4057 by NAT_4:9; :: thesis:
4057 = (41 * 98) + 39 ;
hence not 41 divides 4057 by NAT_4:9; :: thesis:
4057 = (43 * 94) + 15 ;
hence not 43 divides 4057 by NAT_4:9; :: thesis:
4057 = (47 * 86) + 15 ;
hence not 47 divides 4057 by NAT_4:9; :: thesis:
4057 = (53 * 76) + 29 ;
hence not 53 divides 4057 by NAT_4:9; :: thesis:
4057 = (59 * 68) + 45 ;
hence not 59 divides 4057 by NAT_4:9; :: thesis:
4057 = (61 * 66) + 31 ;
hence not 61 divides 4057 by NAT_4:9; :: thesis:

end;

then for n being Element of NAT st 1 < n & n * n <= 4057 & n is prime holds
not n divides 4057 by XPRIMET1:36;
hence 4057 is prime by NAT_4:14; :: thesis: