A152136 a(0) = 0; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that the concatenation of any two consecutive digits in the sequence is a prime.

0, 2, 3, 7, 9, 71, 73, 79, 711, 713, 717, 971, 973, 1111, 1113, 1117, 1119, 7111, 7113, 7117, 9711, 9713, 11111, 11113, 11117, 11119, 71111, 71113, 71117, 97111, 97113, 111111, 111113, 111117, 111119, 711111, 711113, 711117, 971111

Offset: 0

Author

N. J. A. Sloane, Sep 24 2009

Keywords

• nonn
• base

Comments

A variant of A152607 suggested by Zak Seidov, Sep 24 2009.

Computed by Jean-Marc Falcoz.

Comment from Jean-Marc Falcoz: (Start)

The sequence is infinite since it has the following structure:

9713, 11111, 11113, 11117, 11119, 71111, 71113, 71117, 97111,

97113, 111111, 111113, 111117, 111119, 711111, 711113, 711117, 971111,

971113, 1111111, 1111113, 1111117, 1111119, 7111111, 7111113, 7111117, 9711111,

9711113, 11111111, 11111113, 11111117, 11111119, 71111111, 71111113, 71111117, 97111111,

97111113, 111111111, 111111113, 111111117, 111111119, 711111111, 711111113, 711111117, 971111111,

971111113, 1111111111, 1111111113, 1111111117, 1111111119, 7111111111, 7111111113, 7111111117, 9711111111,

9711111113, ... (End)

Links

• Eric Angelini, Chiffres consecutifs dans quelques suites
• E. Angelini, Chiffres consecutifs dans quelques suites [Cached copy, with permission]

Crossrefs

Cf. A152607, A158652, A152604-A152609.

Extensions

Offset changed by N. J. A. Sloane, Jun 16 2021