Determine all possible quadruplets (p, q, r, s) of positive integers with p< = q< = r satisfying the equation p! + q! + r! = 2^s.

 10   for Tot=1 to 1000000
 20   for P=1 to int(Tot/3)
 30   for Q=P to int((Tot-P)/2)
 40   R=Tot-P-Q
 50   Sp2=!(P)+!(Q)+!(R)
 60   S=int(log(Sp2)/log(2)+0.5)
 70   if 2^S=Sp2 then print P;Q;R;S
 80   next
 90   next
100   next

was allowed to run until the total of p+q+r got to 512 and found only

p  q  r  s
1  1  2  2
1  1  3  3
2  3  4  5
2  3  5  7

 

 

Posted by Charlie on 2007-07-03 10:31:57