%I #3 Mar 30 2012 17:26:21
%S 71820,103950,127764,135660,141360,161460,173250,183744,193284,203580,
%T 206712,209440,214830,217620,221760,223020,223860,234432,243540,
%U 244440,246330,247752,256680,263160,264180,265200,280368,281160,286380,287712
%N Numbers taking exactly 21 steps to reach 15 in A086793.
%C Some trajectories are: 71820,1104,168,102,36,46,18,30,27,22,9,13,5,6,12,19,11,3,4,7,8,15 103950,1134,168,... 127764,924,168,... 135660,1134,168,... 221760,1908,162,66,36,... 343728,1650,162,... 376992,2016,297,66,36,... All trajectories eventually join one of previous trajectories. In the first 136 terms <800000 there is only one odd number, 628425. Next odd terms are: 824175, 1340325, 1422135, 1495725 (see A119398).
%Y Cf. A086793, A119396-A119415.
%K base,nonn
%O 1,1
%A _Zak Seidov_, May 18 2006
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