Using Pari/gp (< 1s) gp > isprime((10^11-1)/9+8*10^10+8*10^5+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^17-1)/9+8*10^16+8*10^8+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^61-1)/9+8*10^60+8*10^30+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^95-1)/9+8*10^94+8*10^47+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^119-1)/9+8*10^118+8*10^59+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^139-1)/9+8*10^138+8*10^69+8) %1 = 1
Using Pari/gp (< 1s) gp > isprime((10^169-1)/9+8*10^168+8*10^84+8) %1 = 1
Using Pari/gp (time = 24min, 42,594 ms) gp > default(parisizemax,"1G") gp > isprime((10^1913-1)/9+10^1912*8+10^956*8+8) %1 = 1
Proven by certificate by Masaki UKAI (August 22, 2022) http://factordb.com/index.php?id=1100000002736129756
C:\pfgw>pfgw64 -q"(10^11011-1)/9+8*10^11010+8*10^5505+8" PFGW Version 4.0.4.64BIT.20221214.Win_Dev [GWNUM 30.11] (10^11011-1)/9+8*10^11010+8*10^5505+8 is 3-PRP! (0.7360s+0.0004s) Note that its length, i.e. 11011, is palindromic as well!
C:\pfgw>pfgw64 -q"(10^12539-1)/9+8*10^12538+8*10^6269+8" PFGW Version 4.0.4.64BIT.20221214.Win_Dev [GWNUM 30.11] (10^12539-1)/9+8*10^12538+8*10^6269+8 is 3-PRP! (0.8442s+0.0009s)
C:\pfgw>pfgw64 -q"(10^18583-1)/9+8*10^18582+8*10^9291+8" PFGW Version 4.0.4.64BIT.20221214.Win_Dev [GWNUM 30.11] (10^18583-1)/9+8*10^18582+8*10^9291+8 is 3-PRP! (1.6775s+0.0007s)
C:\pfgw>pfgw64 -q"(10^43535-1)/9+8*10^43534+8*10^21767+8" PFGW Version 4.0.4.64BIT.20221214.Win_Dev [GWNUM 30.11] (10^43535-1)/9+8*10^43534+8*10^21767+8 is 3-PRP! (11.3079s+0.0005s)
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