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%I #7 Apr 23 2023 17:22:52
%S 2,4,12,72,864,20736,933120,117573120,42326323200,36315985305600,
%T 146426052752179200,1475974611741966336000,37784950060594338201600000,
%U 2031318915257551621718016000000,212719716805770805826310635520000000
%N a(1) = 2, a(n+1) = a(n)*{tau(a(n))}.
%C a(1) = 1, a(n+1) = a(n) + tau(a(n)) gives A064491.
%e a(4) = 72 and tau(72)= 12, hence a(5) = 72*12= 864.
%t NestList[# DivisorSigma[0,#]&,2,20] (* _Harvey P. Dale_, Apr 23 2023 *)
%o (PARI) for(n=1,16,if(n==1,a=2,a*=numdiv(a)); print(a); )
%Y Cf. A064491.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Jul 06 2003
%E More terms from _Ray Chandler_, Jul 16 2003
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