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 A221868 Lexicographically earliest sequence of distinct primes in which the concatenation of any number of consecutive terms is composite. 1

%I #19 Apr 04 2015 21:46:57

%S 2,5,11,13,29,31,17,19,43,7,37,41,71,47,67,89,3,101,23,109,59,83,103,

%T 73,107,157,53,127,149,61,131,139,79,163,191,193,97,113,137,167,211,

%U 181,151,197,199,173,223,239,227,179,241,251,229,257,313,233,263,277,271,283,307,347,269,293

%N Lexicographically earliest sequence of distinct primes in which the concatenation of any number of consecutive terms is composite.

%C This sequence is very likely a permutation of the primes.

%H Hans Havermann, <a href="/A221868/b221868.txt">Table of n, a(n) for n = 1..1500</a>

%e Start with 2. The second term cannot be 3 because the concatenation of 2 and 3 is prime. However, 5 works. The third term cannot be 3 because the concatenation of 5 and 3 is prime. It cannot be 7 because the concatenation of 2 and 5 and 7 is prime. However, 11 works.

%K nonn,base

%O 1,1

%A _Hans Havermann_, Apr 10 2013

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Last modified June 8 14:02 EDT 2023. Contains 363165 sequences. (Running on oeis4.)