The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97, and 7. Similarly we can work from right to left: and 3797, 379, 37, and 3.
The aim is to find the sum of the n (between 8 and 11) primes that are both truncatable from left to right and right to left. Begin by entering the number.
NOTE: 2, 3, 5, and 7 are not considered to be truncatable primes.