Hi,

I thought I'd whip this one up for the competition. Not the most efficient but best I could do under the crippled TI-Basic that comes with TI-Nspires.

Calculator type: TI-Nspire
Language: TI-BASIC
File format: .tns
Time to calculate 42nd prime palindrome (on CX CAS): 15.5s

For primality testing, it uses trial division up to square root of x. I wasn't able to implement a sieve or more advanced primality tests mostly due to the language barriers.

For palindromes, it bruteforces though each palindrome in order and tests for primality. When the nth one is found, it displays it to the screen.

Palindromes are made by using a lot of mod and floor magic. The number of digits determined by log10'ing the number and flooring the result. Similar to bit-shifting but for base 10.

No other fancy algorithms.

To run:

Either use:

palprime(n) where n is the nth prime palindrome
or
palprem(n)

Cheers,
tangrs
(	Daniel Tang )