A211683 Numbers > 100 such that all the substrings of length = 2 are primes.

111, 113, 117, 119, 131, 137, 171, 173, 179, 197, 231, 237, 297, 311, 313, 317, 319, 371, 373, 379, 411, 413, 417, 419, 431, 437, 471, 473, 479, 531, 537, 597, 611, 613, 617

Offset: 1

Author

Hieronymus Fischer, Jun 08 2012

Keywords

• nonn
• base

Comments

Only numbers > 100 are considered, since all 2-digit primes are trivial members. See A069488 for the sequence with prime terms > 100.

The sequence is infinite (for example, consider the continued concatenation of ‘11’ or of ‘13’: 111, 1111, 11111, ..., 131, 1313, 13131, ... are members).

Infinitely many terms are palindromic.

Examples

			a(2)=113, since all substrings of length = 2 are primes (11 and 13).
a(10)=197, since all substrings of length = 2 (19, 97) are primes.
		

Links

• Hieronymus Fischer, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A019546, A035232, A039996, A046034, A069488, A085823, A131648, A211681, A211682.