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Smallest prime that remains prime when a string of n 1's is prepended to it.
1

%I #10 Jul 31 2015 02:26:38

%S 2,3,3,7,3,83,31,7,3,29,3,53,23,439,23,53,31,71,31,79,89,233,7,3,227,

%T 487,281,31,7,227,47,439,29,47,349,491,43,31,23,7,919,701,229,283,281,

%U 59,223,2693,53,67,239,2011,2113,467,41,601,587,311,337,2879,59,619,71

%N Smallest prime that remains prime when a string of n 1's is prepended to it.

%e a(3)=7 because it is the first prime before 31,59,61,71,73,97,... all remaining prime when 111 is prepended to each of them.

%t f[n_] := Block[{k = 1, t = Table[1, {n}]}, While[id = IntegerDigits[ Prime[k]]; id[[1]] == 1 || !PrimeQ[ FromDigits[ Join[t, id]]], k++ ]; Prime[k]]; Table[ f[n], {n, 0, 62}] (* _Robert G. Wilson v_, Apr 09 2005 *)

%Y Cf. A105436, A065584.

%K nonn,base

%O 0,1

%A _Lekraj Beedassy_, Apr 08 2005

%E More terms from _Robert G. Wilson v_, Apr 09 2005