%I #12 Sep 13 2024 03:32:40
%S 1,2,6,40,1608,2585680,6685741062420,44699133553728910336256592,
%T 1998012540454093724746522398047564450017935663454544
%N a(0) = 1, a(n+1) = a(n)^2 + number of divisors of a(n).
%H <a href="/index/Aa#AHSL">Index entries for sequences of form a(n+1)=a(n)^2 + ...</a>
%F a(n) = A000290(a(n-1)) + A000005(a(n-1)).
%t NestList[#^2+DivisorSigma[0,#]&,1,10] (* _Harvey P. Dale_, Nov 18 2022 *)
%Y Cf. A007018.
%K nonn
%O 0,2
%A _Reinhard Zumkeller_, May 09 2006