%I A075616
%S A075616 2,1,3,4,7,5,9,6,17,8,43,10,19,11,13,12,33,14,37,15,23,16,113,18,73,20,
%T A075616 51,21,103,22,61,24,87,25,49,26,67,27,117,28,57,29,71,30,79,31,283,32,
%U A075616 239,34,81,35,143,36,151,38,139,39,147,40,289,41,161,42,351,44,129,45
%N A075616 Rearrangement of natural numbers so that starting with a(n) the concatenation 
               of n numbers gives a prime.
%t A075616 a = {2, 1, 3}; f[n_] := Block[{k = 1, b = Take[a, {n, 2n - 3}]}, While[Position[a, 
               k] != {}, k++ ]; b = Join[b, IntegerDigits[k]]; a = Append[a, k]; 
               While[ Position[a, k] != {} || !PrimeQ[ FromDigits[ Join[ b, IntegerDigits[k]]]], 
               k++ ]; a = Append[a, k]]; Do[ f[n], {n, 3, 40}]; a
%Y A075616 Cf. A075617 and A073672.
%Y A075616 Sequence in context: A139374 A111958 A160187 this_sequence A160186 A050041 
               A058658
%Y A075616 Adjacent sequences: A075613 A075614 A075615 this_sequence A075617 A075618 
               A075619
%K A075616 base,nonn
%O A075616 1,1
%A A075616 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 29 2002
%E A075616 Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 02 
               2002