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%I #11 Apr 12 2024 10:47:56
%S 1,4,2,5,8,3,14,18,30,22,43,25,41,44,38,23,58,33,63,55,16,24,10,17,27,
%T 15,21,31,49,32,45,28,7,20,11,40,12,9,13,37,47,36,29,60,59,35,52,19,
%U 53,79,34,65,42,50,54,39,61,62,66,46,64,6,26,71,48,51,57,56,68,75,67,78,74,70,69,72
%N a(1) = 1; for n > 1, a(n) is the smallest unused positive number such that 2^a(n) contains a(n-1) as a substring.
%C The sequence is conjectured to be a permutation of the positive integers.
%H Scott R. Shannon, <a href="/A371904/b371904.txt">Table of n, a(n) for n = 1..10000</a>
%e a(2) = 4 as 2^4 = 16 which contains a(n-1) = a(1) = '1' as a substring.
%e a(7) = 14 as 2^14 = 16384 which contains a(n-1) = a(6) = '3' as a substring. Note that 2^5 = 32 also contains '3' as a substring but 5 has already been used.
%Y Cf. A000079, A063565, A371918, A368866.
%K nonn,base
%O 1,2
%A _Scott R. Shannon_, Apr 11 2024