This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A321339 #18 May 28 2019 15:33:00
%S A321339 1,2,18,4085658,94856826320432984953640661130233988218
%N A321339 a(1)=1; thereafter a(n) = a(n-1) * prime(a(n-1))^(n-1).
%C A321339 The prime factorization of a(n) describes all previous terms in the sequence: a(n) = prime(a(1))^1 * prime(a(2))^2 * prime(a(3))^3 * ...* prime(a(n-1))^(n-1).
%C A321339 An infinite and monotonically increasing sequence. Grows fast enough that a(6) and later terms are too large to display in full.
%e A321339 4085658 = 2 * 3^2 *61^3 = prime(1)^1 * prime(2)^2 * prime(18)^3. The previous values in the sequence can be read from this factorization: the 3rd is 18, the 2nd is 2, the 1st is 1.
%t A321339 Nest[Append[#, #[[-1]] Prime[#[[-1]] ]^Length@ #] &, {1}, 4] (* _Michael De Vlieger_, Nov 05 2018 *)
%t A321339 nxt[{n_,a_}]:={n+1,a*Prime[a]^n}; NestList[nxt,{1,1},4][[All,2]] (* _Harvey P. Dale_, May 28 2019 *)
%o A321339 (PARI) apply( a(n) = prod(i=1, n-1, prime(a(i))^i), [1..5] )
%Y A321339 Somewhat similar to A007097.
%Y A321339 Cf. A321340.
%K A321339 nonn
%O A321339 1,2
%A A321339 _Russell Y. Webb_, Nov 05 2018