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%I A063506 #14 Mar 10 2019 17:07:33
%S A063506 3,4,6,8,16,40,128,512,2560,20480,212992,2949120,80216064,3019898880,
%T A063506 130459631616,7827577896960,935134639423488,128247036263792640,
%U A063506 22024291027701989376,7222873082376801484800,4118350906606118082969600
%N A063506 a(n) = phi(a(n-1)) * number of divisors of a(n-1), a(1)=3.
%H A063506 Harry J. Smith, <a href="/A063506/b063506.txt">Table of n, a(n) for n = 1..148</a>
%t A063506 NestList[EulerPhi[#]DivisorSigma[0,#]&,3,20] (* _Harvey P. Dale_, Mar 10 2019 *)
%o A063506 (PARI) s(n)=if(n<2,n+2,eulerphi(s(n-1))*numdiv(s(n-1)) ); for(n=1,22,print(s(n)))
%o A063506 (PARI) { for (n=1, 148, if (n>1, a=eulerphi(a)*numdiv(a), a=3); write("b063506.txt", n, " ", a) ) } \\ _Harry J. Smith_, Aug 24 2009
%K A063506 nonn
%O A063506 1,1
%A A063506 _Jason Earls_, Aug 09 2001

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