A152136 - OEIS

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.

%I #11 Jun 16 2021 18:25:27

%S 0,2,3,7,9,71,73,79,711,713,717,971,973,1111,1113,1117,1119,7111,7113,

%T 7117,9711,9713,11111,11113,11117,11119,71111,71113,71117,97111,97113,

%U 111111,111113,111117,111119,711111,711113,711117,971111

%N 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.

%C A variant of A152607 suggested by _Zak Seidov_, Sep 24 2009.

%C Computed by _Jean-Marc Falcoz_.

%C Comment from _Jean-Marc Falcoz_: (Start)

%C The sequence is infinite since it has the following structure:

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

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

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

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

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

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

%C 9711111113, ... (End)

%H Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/ConsecDig.htm">Chiffres consecutifs dans quelques suites</a>

%H E. Angelini, <a href="/A152136/a152136.pdf">Chiffres consecutifs dans quelques suites</a> [Cached copy, with permission]

%Y Cf. A152607, A158652, A152604-A152609.

%K nonn,base

%O 0,2

%A _N. J. A. Sloane_, Sep 24 2009

%E Offset changed by _N. J. A. Sloane_, Jun 16 2021