1,1

Conjecture: next terms are 1111111111111111111 and 11111111111111111111111.

Table of n, a(n) for n=1..20.

Prime 179 is a term because 197 and 719 are also prime.

Prime 1913 is not a term because 9113 is not prime (even though 1193, 1319, 1931 and 3911 are primes).

Cf. A003459 (absolute primes).

Subsequence of A069706 (primes with property that swapping first and last digits also gives a prime).

Sequence in context: A105892 A111337 A266675 * A240570 A162237 A325870

Adjacent sequences: A185101 A185102 A185103 * A185105 A185106 A185107

nonn,base,less

Jaroslav Krizek, Dec 26 2012

approved