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%I #2 Mar 31 2012 14:40:13
%S 1,2,4,16,1458,2918430506250,
%T 7164640537512654203797788776525821310188011060
%N a(1)=1, a(n)=p_i^d_i where p_i is i-th prime and d_i is i-th digit of a(n-1).
%C Or a(n-1)= decimal encoding of the prime factorization of a(n). Cf. A068633 Let n = p^a*q^b... then a(n) = concatenation paqb..., A067599 Decimal encoding of the prime factorization of n.
%e a(4)=16, a(5)=2^1 * 3^6 = 1458;
%e a(6)= 2^1 * 3^4 * 5^5 * 7^8 = 2918430506250.
%t a[1]=1;id[n_]:=id[n]=IntegerDigits[a[n-1]]; a[n_]:=a[n]= Times@@Table[Prime[i]^id[n][[i]],{i,1,Length[id[n]]}]; {1,Table[a[n],{n,2,7}]}//Flatten
%Y Cf. A067599, A068633.
%K base,nonn
%O 1,2
%A _Zak Seidov_, Dec 16 2006
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