A075077 - OEIS

%I #5 Dec 05 2013 19:55:36

%S 1,3,5,4,2,8,6,9,7,11,10,12,13,14,16,17,15,19,20,18,22,23,21,25,24,26,

%T 28,27,29,31,32,30,34,35,33,37,38,36,40,41,39,43,42,44,46,45,47,48,50,

%U 49,51,53,52,54,56,55,57,58,59,60,61,62,63,65,64,66,67,68,70,71,69,73

%N a(1) =1 and then the smallest number not occurring earlier such that a(n)+a(n+1) gives a different composite number (not obtained earlier).

%e 19 (not 18) follows 15 though 15+18 = 33 is also composite but 33 is already obtained as 16 +17.

%Y Cf. A075078.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Sep 09 2002

%E More terms from _Sascha Kurz_, Feb 01 2003