pg(215+1763*307k)
 

pg(215) and pg(541456) are probable primes




215 and 541456 are 215 mod 307


with pfgw I tried if are probable primes:


pg(215+1763*307*2), pg(215+1763*307*3)...


upto pg(215+1763*307*18) the numbers have all very small factors...so they are not probable prime...


whereas pg(215+1763*307*19) has no small factor and I am running a prp test on it