Define the sequence A(n) as:
A(1) = 1, A(2) =13, A(3) = 131, A(4) = 1313,...

- Determine the minimum value of n such that A(n) is divisible by 29.
- What is the general form of n such that A(n) is divisible by 29?

131313131 does it.

n....9 digits fits.

28 digits fits as well.

Edited, after seeing Ch's program's results:

**The valid n are congruent to 0 mod 28 **** or 9 mod 28:**

**i.e. n=9,28,37,56 etc**

*Edited on ***January 14, 2014, 2:29 pm**