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 A333120 #7 Mar 08 2020 08:39:06
%S A333120 1,1,2,5,27,730,532906,283988804837,80649641272747674596596,
%T A333120 6504364637422885153991868441922618991334787221,
%U A333120 42306759336557340251452848811862268800945638555088445693345741249091605099189510505344903572
%N A333120 a(1) = 1, a(n+1) = Sum_{d|n} a(d)^2.
%F A333120 a(n) ~ c^(2^n), where c = 1.10850959824748299278192262396861284785509520261602375885447280659977154... - _Vaclav Kotesovec_, Mar 08 2020
%t A333120 a[1] = 1; a[n_] := a[n] = Sum[a[d]^2, {d, Divisors[n - 1]}]; Table[a[n], {n, 1, 11}]
%Y A333120 Cf. A003238, A007018, A082588.
%K A333120 nonn
%O A333120 1,3
%A A333120 _Ilya Gutkovskiy_, Mar 08 2020