custom code : trial division to 10^8
GMP 4.2-ECM 6.1 : PRP
PrimeForm v. 0.4 Upd.4 : PRP bases 11 , 13 , 233 , 241 , 251
custom code : strongly-probable prime to prime bases
61962811 , 61963619 , 61977551 , 61979837
and 5 others
Define np ( n1 ) = n1^n1 + (n1+1)^(n1+1) .
Let a = 4223 .
Let p = np ( a ) / ( 233 * 185531746148849 ) .
p is an 15299-digit strongly-probable prime .
p*(p-1) + a has 30597 digits .
np ( p*(p-1) + a ) has more .
p divides np ( p*(p-1) + a ) .

To be completed...