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a(1) = 1; a(n) = smallest positive integer not already used which has a prime signature different from a(n-1), a(n-1)+1 and a(n-1)-1.
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%I #2 Mar 31 2012 14:41:48

%S 1,4,6,8,10,12,9,2,14,16,18,15,3,20,24,21,5,27,7,25,11,30,22,28,26,13,

%T 32,36,40,42,33,17,34,19,35,23,44,38,45,29,39,31,46,48,50,37,49,41,51,

%U 43,54,52,56,47,60,55,53,57,59,63,61,64,66,68,70,72,58,75,67,62,78,76

%N a(1) = 1; a(n) = smallest positive integer not already used which has a prime signature different from a(n-1), a(n-1)+1 and a(n-1)-1.

%C A permutation of the positive integers.

%e To compute a(8), we see a(7) is 9; we look for the smallest unused positive integer that does not have the same prime signature as either 8, 9 or 10. The first such number is 2.

%Y Cf. A179371

%K nonn

%O 1,2

%A _Will Nicholes_, Jul 11 2010