A238647 Primes which are not the concatenation of two primes.

2, 3, 5, 7, 11, 13, 17, 19, 29, 31, 41, 43, 47, 59, 61, 67, 71, 79, 83, 89, 97, 101, 103, 107, 109, 127, 131, 139, 149, 151, 157, 163, 167, 179, 181, 191, 199, 227, 239, 251, 257, 263, 269, 277, 281, 307, 349, 401, 409, 419, 421, 431, 439, 443, 449, 457, 461

Offset: 1

Author

Colin Barker, Mar 02 2014

Keywords

• nonn
• base

Comments

223 is the first term in A141409 which is not in this sequence.

In this sequence, a prime preceded by one or more zeros is not considered to be a prime.

Examples

			59 is in the sequence because 5 is prime but 9 is not prime.
223 is not in the sequence because both 2 and 23 are primes.
		

Crossrefs

Cf. A141409, A105184 (complement), A238056, A238057, A238499.