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 A371441 #16 Apr 19 2024 08:39:07
%S A371441 1,4,37,1000,81001,19683244,14349084877,31381448626000,
%T A371441 205893684435186001,4052605390737766057684,
%U A371441 239302295717674347940182517,42391683779498857714559512339000,22528678819460652442683221796950499001,35917990801478965784376042224979510418771324
%N A371441 a(n) = a(n-1)*3^n + 1 where a(0)=1.
%F A371441 a(n) = Sum_{k=0..n} 3^(k*(2*n + 1 - k)/2). - _Vaclav Kotesovec_, Apr 10 2024
%t A371441 Table[Sum[3^(k*(2*n + 1 - k)/2), {k, 0, n}], {n, 0, 15}] (* _Vaclav Kotesovec_, Apr 10 2024 *)
%t A371441 Block[{n = 0}, NestList[#*3^++n + 1 &, 1, 15]] (* _Paolo Xausa_, Apr 19 2024 *)
%o A371441 (Python)
%o A371441 l = [1]
%o A371441 for i in range(1,14):
%o A371441 l.append(l[-1]*pow(3,i) + 1)
%o A371441 print(l)
%Y A371441 Cf. A073587, A178185.
%K A371441 nonn,easy
%O A371441 0,2
%A A371441 _Alexandre Herrera_, Mar 23 2024