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A262282 a(1)=11. For n>1, let s denote the digit-string of a(n-1) with the first digit omitted. Then a(n) is the smallest prime not yet present which starts with s. 4

%I

%S 11,13,3,2,5,7,17,71,19,97,73,31,101,103,37,79,907,701,107,709,911,

%T 113,131,311,1103,1031,313,137,373,733,331,317,173,739,397,971,719,

%U 191,919,193,937,379,797,977,773,7307,307,727,271,7103,1033,337,3701,7013

%N a(1)=11. For n>1, let s denote the digit-string of a(n-1) with the first digit omitted. Then a(n) is the smallest prime not yet present which starts with s.

%C If a(n-1) has a single digit then a(n) is simply the smallest missing prime.

%C Leading zeros in s are ignored.

%C The b-file suggests that there are infinitely many primes that do not appear in the sequence. However, there is no proof at present that any particular prime (23, say) never appears.

%C _Alois P. Heinz_ points out that this sequence and A262283 eventually merge (see the latter entry for details). - _N. J. A. Sloane_, Sep 19 2015

%C A variant without the prime number condition: A262356. - _Reinhard Zumkeller_, Sep 19 2015

%H Alois P. Heinz, <a href="/A262282/b262282.txt">Table of n, a(n) for n = 1..705</a>

%e a(1)=11, so s=1, a(2) is smallest missing prime that starts with 1, so a(2)=13. Then s=3, so a(3)=3. Then s is the empty string, so a(4)=2, and so on.

%o (Haskell)

%o import Data.List (isPrefixOf, delete)

%o a262282 n = a262282_list !! (n-1)

%o a262282_list = 11 : f "1" (map show (delete 11 a000040_list)) where

%o f xs pss = (read ys :: Integer) :

%o f (dropWhile (== '0') ys') (delete ys pss)

%o where ys@(_:ys') = head $ filter (isPrefixOf xs) pss

%o -- _Reinhard Zumkeller_, Sep 19 2015

%Y Suggested by A089755. Cf. A262283.

%Y Cf. A262356.

%K nonn,base

%O 1,1

%A _Franklin T. Adams-Watters_ and _N. J. A. Sloane_, Sep 18 2015

%E More terms from _Alois P. Heinz_, Sep 18 2015

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Last modified June 24 18:46 EDT 2021. Contains 345419 sequences. (Running on oeis4.)