306046

Appears in sequences

• Values of n for which the concatenations 1nn1, 3nn3, 7nn7 and 9nn9 are all primes.at n=18A102504
• a(1)=1, a(2)=2. a(n) is the a(n-1)th integer from among those positive integers coprime to a(n-2).at n=33A126881