Palindromic Merlon Primes - Program Outputs

4*(10⁵-1)/9 + 5*10⁴ + 5*10² + 5

Using Pari/gp (< 1s)
     gp > isprime(4*(10^5-1)/9+5*10^4+5*10^2+5)
     %1 = 1

4*(10¹¹-1)/9 + 5*10¹⁰ + 5*10⁵ + 5

Using Pari/gp (< 1s)
     gp > isprime(4*(10^11-1)/9+5*10^10+5*10^5+5)
     %1 = 1

4*(10¹⁷-1)/9 + 5*10¹⁶ + 5*10⁸ + 5

Using Pari/gp (< 1s)
     gp > isprime(4*(10^17-1)/9+5*10^16+5*10^8+5)
     %1 = 1

4*(10⁴³-1)/9 + 5*10⁴² + 5*10²¹ + 5

Using Pari/gp (< 1s)
     gp > isprime(4*(10^43-1)/9+5*10^42+5*10^21+5)
     %1 = 1

4*(10¹⁰²¹-1)/9 + 5*10¹⁰²⁰ + 5*10⁵¹⁰ + 5

Using Pari/gp (time = 1min, 47,610 ms)
     gp > default(parisizemax,"1G")
     gp > isprime(4*(10^1021-1)/9+5*10^1020+5*10^510+5)
     %1 = 1

Patrick De Geest - Belgium