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, 619, 671, 673, 679, 711, 713, 717, 719, 731, 737, 797, 831, 837, 897, 971, 973, 979, 1111

Offset

1,1

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.

Links

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

Example

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.

Crossrefs

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

Sequence in context: A104155 A395128 A133786 * A326109 A338111 A351060

Adjacent sequences: A211680 A211681 A211682 * A211684 A211685 A211686

Keyword

nonn,base

Author

Hieronymus Fischer, Jun 08 2012

Status

approved