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a(1) = 7. For n > 1, a(n) is the least unused number such that every concatenation a(n)a(n-1)...a(2)a(1) is prime.
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%I #6 Mar 30 2012 17:29:13

%S 7,1,3,6,2,21,10,9,8,37,20,25,29,72,28,30,27,23,39,19,51,32,22,54,42,

%T 35,24,73,36,120,44,186,4,26,126,171,70,33,18,60,113,99,81,76,47,108,

%U 91,170,159,49,65,114,238,185,285,34,98,312,63,183,15,205,230,198,310,524

%N a(1) = 7. For n > 1, a(n) is the least unused number such that every concatenation a(n)a(n-1)...a(2)a(1) is prime.

%C Is this a rearrangement of the natural numbers?

%Y Cf. A089710, A089711, A089560-A089573.

%K base,nonn

%O 1,1

%A _Ray Chandler_, Nov 22 2003

%E Edited by _Charles R Greathouse IV_, Apr 29 2010