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 A120145 #7 May 14 2023 12:37:36
%S A120145 20,30,45,68,102,153,229,344,516,774,1161,1741,2612,3918,5877,8815,
%T A120145 13223,19834,29751,44627,66940,100410,150615,225923,338884,508326,
%U A120145 762489,1143734,1715601,2573401,3860102,5790153,8685229,13027844
%N A120145 a(n) = 20 + floor( (1 + Sum_{j=1..n-1} a(j)) / 2 ).
%H A120145 G. C. Greubel, <a href="/A120145/b120145.txt">Table of n, a(n) for n = 1..1000</a>
%t A120145 a[n_]:= a[n]= 20 +Quotient[1 +Sum[a[k], {k,n-1}], 2];
%t A120145 Table[a[n], {n,60}] (* _G. C. Greubel_, May 14 2023 *)
%o A120145 (SageMath)
%o A120145 @CachedFunction
%o A120145 def A120145(n): return 20 + (1+sum(A120145(k) for k in range(1,n)))//2
%o A120145 [A120145(n) for n in range(1,61)] # _G. C. Greubel_, May 14 2023
%Y A120145 Cf. A073941, A072493, A112088, A120134 - A120144, A120146 - A120209.
%K A120145 nonn
%O A120145 1,1
%A A120145 _Graeme McRae_, Jun 10 2006