Palindromic Merlon Primes - Program Outputs

7*(10⁷-1)/9 + 2*10⁶ + 2*10³ + 2

Using Pari/gp (< 1s)
     gp > isprime(7*(10^7-1)/9+2*10^6+2*10^3+2)
     %1 = 1

7*(10⁸³-1)/9 + 2*10⁸² + 2*10⁴¹ + 2

Using Pari/gp (< 1s)
     gp > isprime(7*(10^83-1)/9+2*10^82+2*10^41+2)
     %1 = 1

7*(10⁵⁹⁹-1)/9 + 2*10⁵⁹⁸ + 2*10²⁹⁹ + 2

Using Pari/gp (time = 13,422 ms)
     gp > default(parisizemax,"1G")
     gp > isprime(7*(10^599-1)/9+2*10^598+2*10^299+2)
     %1 = 1

Patrick De Geest - Belgium