Posted 2 Months, 3 Weeks ago Terragen Senior Boarder Posts: 65   (I don't know how difficult this puzzle is.) Let a(m,k) = 1 The administrator has disabled public write access. Posted 2 Months, 3 Weeks ago Duane Expert Boarder Posts: 84   Substitute the definition of a(m,k) in the sum; reverse the order of the two summations; the inner summation can now be calculated exactly and is half an integer. I make it 2, *5*, 10, 15, 24, 30, 43, 52 ... Mike Guy The administrator has disabled public write access. Posted 2 Months, 3 Weeks ago Chant Dhames Senior Boarder Posts: 71   Your mindspring.com address is bouncing... This is a request for clarification. Can you clarify the notation sum{j|k}? I don't think you mean 'Sum from j=1 to k', do you? Regards, B Repetto Click here to contact me by email http://cerbermail.com/?C4ikKnQCRA The administrator has disabled public write access. Posted 2 Months, 3 Weeks ago Mirelo Expert Boarder Posts: 87   It usually means to sum over the divisors of k. The administrator has disabled public write access.