grb=307, 311, 313, 317, 331, 337, 347, 349
grb=353, 359, 367, 373, 379, 383, 389, 397
n=3 to 100k done

the following prp were found

grb=307 n=53, 1201, 6011
grb=311 n=36497
grb=313 n=109, 173, 1193
grb=317 n=157, 6529, 39107
grb=331 n=25033
grb=337 n=5, 19, 2099
grb=347 n=337, 401, 3331, 7547
grb=349 n=7, 17, 107, 38167
grb=353 n=7, 9767, 71143
grb=359 n=5, 59, 101, 383, 74189, 98327
grb=367 n=239
grb=373 n=5, 13, 23
grb=379 n=17, 31, 16729
grb=383 n=3, 17, 199, 307, 1093
grb=389 n=11, 19
grb=397 n=5, 13

To be completed...