Find all integers n such that S(n) = S(2n) = ... = S(n*n), where S is the sum of the base-10 digits.

(In reply to computer exploration--no proof by Charlie)

Well, that suffered from lack of precision.

With DEFDBL A-Z, we see that 9999 as well as 99999 and 999999 and 9999999 also work.

I'm assuming it works for all 10^k-1.

Posted by Charlie on 2012-11-22 12:14:06