%I #16 Apr 19 2021 15:45:52
%S 6,55,111,334,335,671,1343,16117,16118,64473,64474,257897,2063177,
%T 8252709,41263546,123790639,371371918,1485487673,2970975347,
%U 59419506941,356517041647,5704272666353,11408545332707,262396542652262
%N a(1) = 6, a(n) = smallest number of the form k*a(n-1) + 1 with the same number of divisors, i.e., 4.
%C Though the initial terms match, this sequence differs from A085066, in that the terms can be of two prime signatures, i.e., p*q and p^3 such that tau(p*q) = tau(p^3) = 4.
%H Amiram Eldar, <a href="/A085067/b085067.txt">Table of n, a(n) for n = 1..90</a>
%t v = 6; Print[v]; Do[k = 1; While[DivisorSigma[0, k*v + 1] != 4, k++ ]; v = k*v + 1; Print[v], {n, 2, 30}] (* _Ryan Propper_, Aug 29 2005 *)
%t snsnd[n_]:=Module[{k=1},While[DivisorSigma[0,k*n+1]!=4,k++];k*n+1]; NestList[ snsnd,6,30] (* _Harvey P. Dale_, Apr 19 2021 *)
%Y Cf. A085066.
%K nonn
%O 1,1
%A _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 29 2003
%E Corrected and extended by _Ryan Propper_, Aug 29 2005