a = 7 ,b = 5 ,a + b = 12
a = 11 ,b = 2 ,a + b = 13还可以，不过不完整a = (41 - 4b)/3 = 14 - b - (1 + b)/3b = (41 - 3a) /4 < 111 + b 为 3的倍数，且为小于 11 的质数：b 只能是 2、5所以：a = 7 , b = 5 , a + b = 12a = 11 , b = 2 , a + b = 13