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a(n) = the largest numbers m with the number of steps n of iterations of {r - (smallest prime divisor of r)} needed to reach 0 starting at r = m .
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%I #2 Mar 30 2012 19:00:23

%S 4,6,9,10,12,15,16,18,21,25,24,27,28,30,35,34,36,39,40,42,49,46,48,51,

%T 55,54,57,58,60,65,64,66,69,70,77,75,76,78,81,85,84,91,88,90,95,94,96,

%U 99,100,102,105,106,108,111,121,119,117,118,120,125,124,126,133,130,132

%N a(n) = the largest numbers m with the number of steps n of iterations of {r - (smallest prime divisor of r)} needed to reach 0 starting at r = m .

%C A175126(a(n)) = A175126(A005843(n)) = n. [From _Jaroslav Krizek_, May 12 2010]

%e Example (a(4)=9): 9-3=6, 6-2=4, 4-2=2, 2-2=0; iterations has 4 steps and number 9 is the largest number with such result.

%Y Cf. A175126, A046666, A005843.

%K nonn

%O 2,1

%A _Jaroslav Krizek_, Feb 15 2010

%E Edited by R. J. Mathar, Mar 11 2010