A324262 - OEIS

%I #14 Mar 16 2019 13:13:35

%S 0,0,0,0,13731373,1190911909,0,19090911909091,0,0,0,0,0,0,0,0,0,0,0,0,

%T 7316763215964848081373167632159648480813,

%U 111272689909091345969111272689909091345969,10527889691056689261011052788969105668926101,0,0,0,0

%N a(n) is the smallest term of A324261 with 2n digits if it exists, otherwise 0.

%C There can be a large number of terms in A324261 with 2n digits. For example, there are 227 terms with length 66. Selecting only the smallest term for each length allows terms to be listed for larger values of n.

%C The terms of A324261 with length 2n are formed by concatenating two copies of prime p, where p has length n and the decimal representation of p contains all the prime factors of 10^n + 1 as described in A324261 and A083359.

%C Subsequence of A020338 (Doublets: base-10 representation is the juxtaposition of two identical strings).

%H Deron Stewart, <a href="/A324262/b324262.txt">Table of n, a(n) for n = 0..61</a>

%e With m = 27 there are three prime p's: 114175966169705419295257913, 352579141759661697054192911 and 525791141759661697054192913. The smallest p concatenated with itself gives a(27) = 114175966169705419295257913114175966169705419295257913.

%e With m = 28 there are no solutions so a(28) = 0.

%Y Cf. A083359, A020338, A324261, A324257.

%K nonn,base

%O 0,5

%A _Deron Stewart_, Mar 13 2019