A085107 Starting with n-1 go on adding the numbers less than n and coprime to it in descending order until one gets a prime. a(n) = this prime, or 0 if no such number exists.

0, 0, 2, 3, 7, 5, 11, 7, 0, 19, 19, 11, 23, 13, 53, 0, 31, 17, 0, 19, 0, 101, 43, 23, 47, 131, 0, 139, 0, 29, 59, 31, 233, 223, 67, 179, 71, 37, 373, 109, 79, 41, 83, 43, 269, 457, 0, 47, 431, 139, 641, 313, 103, 53, 107, 251, 613, 643, 0, 59, 0, 61, 587, 0, 127, 521, 131, 67