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 A387484 #13 Sep 01 2025 06:54:48
%S A387484 1,0,0,4,8,0,16,128,64,64,1152,2304,768,8192,36864,33792,55296,409600,
%T A387484 823296,704512,3719168,13123584,16351232,33619968,160890880,329515008,
%U A387484 436731904,1695809536,5182586880,7935623168,18086887424,67335356416,141687783424
%N A387484 a(n) = Sum_{k=0..floor(n/3)} 2^(n-k) * binomial(k,n-3*k)^2.
%H A387484 Vincenzo Librandi, <a href="/A387484/b387484.txt">Table of n, a(n) for n = 0..2000</a>
%F A387484 G.f.: 1/sqrt((1-4*x^3-8*x^4)^2 - 128*x^7).
%t A387484 Table[Sum[2^(n-k)*Binomial[k,n-3*k]^2,{k,0,Floor[n/3]}],{n,0,40}] (* _Vincenzo Librandi_, Sep 01 2025 *)
%o A387484 (PARI) a(n) = sum(k=0, n\3, 2^(n-k)*binomial(k, n-3*k)^2);
%o A387484 (Magma) [(&+[2^(n-k)* Binomial(k,n-3*k)^2: k in [0..Floor(n/3)]]): n in [0..40]]; // _Vincenzo Librandi_, Sep 01 2025
%Y A387484 Cf. A387483, A387485.
%K A387484 nonn,new
%O A387484 0,4
%A A387484 _Seiichi Manyama_, Aug 30 2025