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%I #32 Jun 11 2022 18:41:42
%S 5040,7920,8400,9360,10080,10800,11088,11340,11760,12240,12600,12960,
%T 13104,13200,13680,13860,15600,15840,16200,16380,16560,16800,17136,
%U 17640,17820,18000,18144,18720,18900,19152,19440,19800,20160,20400,20592,20880,21060,21168
%N For all n, if d is recursively applied to a(n) exactly 6 times then the fixed point of d-iteration is just reached.
%C Observe that the values giving stationary value in 6 steps are rather large.
%C "d" in the definition refers to the number of divisors of n. - _Harvey P. Dale_, Mar 06 2015
%H Amiram Eldar, <a href="/A036458/b036458.txt">Table of n, a(n) for n = 1..10000</a>
%F A036459(a(n)) = 6. - _Ivan Neretin_, Jan 25 2016
%e a(1)=5040 and the nested d functions are 60,12,6,4,3 and the 6th is 2. a(5)=10080 and iterating d with 10080 initial value, after 6 iterations the convergence takes place through 72,12,6,4,3 transients, i.e., 2 is reached on the 6th step.
%t draQ[n_]:=Length[FixedPointList[DivisorSigma[0,#]&,n,7]]==8; Select[ Range[ 21000],draQ] (* _Harvey P. Dale_, Mar 06 2015 *)
%o (PARI) is(n)=for(i=1,5,n=numdiv(n); if(n<3, return(0))); numdiv(n)==2 \\ _Charles R Greathouse IV_, Sep 17 2015
%Y Cf. A000005, A036457, A036459.
%K nonn
%O 1,1
%A _Labos Elemer_
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