let n be Nat; ( n satisfies_Sierpinski_problem_89 & n <= 201 implies n in {33,85,93,141,201} )
assume that
A1:
n satisfies_Sierpinski_problem_89
and
A2:
n <= 201
and
A3:
not n in {33,85,93,141,201}
; contradiction
( 4 < 6 & 6 <= n )
by A1, Th65;
then A4:
4 < n
by XXREAL_0:2;
set a = n div 4;
set b = n mod 4;
A5:
n = ((n div 4) * 4) + (n mod 4)
by INT_1:59;
A6:
n mod 4 = 1
A7:
n div 4 <> 0
by A4, A5, A6;
((n div 4) * 4) + 1 <= (50 * 4) + 1
by A2, A5, A6;
then
(n div 4) * 4 <= 50 * 4
by XREAL_1:6;
then
( 1 <= n div 4 & n div 4 <= 50 )
by XREAL_1:68, A7, NAT_1:14;
then
not not n = (1 * 4) + 1 & ... & not n = (50 * 4) + 1
by A5, A6;
per cases then
( n = 5 or n = 9 or n = 13 or n = 17 or n = 21 or n = 25 or n = 29 or n = 37 or n = 41 or n = 45 or n = 49 or n = 53 or n = 57 or n = 61 or n = 65 or n = 69 or n = 73 or n = 77 or n = 81 or n = 89 or n = 97 or n = 101 or n = 105 or n = 109 or n = 113 or n = 117 or n = 121 or n = 125 or n = 129 or n = 133 or n = 137 or n = 145 or n = 149 or n = 153 or n = 157 or n = 161 or n = 165 or n = 169 or n = 173 or n = 177 or n = 181 or n = 185 or n = 189 or n = 193 or n = 197 )
by A3, ENUMSET1:def 3;
end;