Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #8 Dec 02 2019 13:59:37
%S 0,1,5,2,4,6,8,3,5,5,7,7,9,9,11,4,6,6,8,6,8,8,27,8,14,10,14,10,31,12,
%T 41,5,33,7,39,7,16,9,20,7,22,9,29,9,26,28,13,9,13,15,30,11,32,15,28,
%U 11,17,32,19,13,40,42,32,6,38,34,15,8,19,40,21,8,21
%N a(n) is the number of iterations needed to reach 1 starting at n and using the map k -> (k/2 if k is even, otherwise k + (largest partition number < k)). Set a(n) = -1 if the trajectory never reaches 1.
%e The trajectory of 15 is [15, 26, 13, 24, 12, 6, 3, 5, 8, 4, 2, 1], taking 11 steps to reach 11. So a(15) = 11.
%Y Cf. A000041.
%K nonn
%O 1,3
%A _Ali Sada_, Nov 13 2019