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 A255269 #14 Feb 16 2025 08:33:25
%S A255269 1,4,864,286654464,7132880358604800000,
%T A255269 993710590042385551668019200000000000,
%U A255269 82086865668400428790437436119503664712777728000000000000000000
%N A255269 a(n) = Product_{k=1..n} k!^k.
%H A255269 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Hyperfactorial.html">Hyperfactorial</a>
%H A255269 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Superfactorial.html">Superfactorial</a>
%F A255269 a(n) = A255268(n) / A055462(n-1).
%F A255269 a(n) ~ sqrt(A) * exp((3 - 45*n^2 - 32*n^3 - 9*Zeta(3)/Pi^2)/72) * n^((8*n^3 + 18*n^2 + 10*n + 1)/24) * (2*Pi)^(n*(n+1)/4), where A = A074962 = 1.28242712910062263687534256886979... is the Glaisher-Kinkelin constant and Zeta(3) = A002117 = 1.2020569031595942853997... .
%t A255269 Table[Product[k!^k,{k,1,n}],{n,1,10}]
%t A255269 FoldList[Times,Table[(k!)^k,{k,10}]] (* _Harvey P. Dale_, Aug 16 2021 *)
%Y A255269 Cf. A000178, A002109, A036740, A055462, A255268.
%K A255269 nonn
%O A255269 1,2
%A A255269 _Vaclav Kotesovec_, Feb 20 2015