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 A183896 #8 Mar 23 2024 20:23:32
%S A183896 0,-1,-2,0,0,-128,-1024,0,0,-4194304,-134217728,0,0,-35184372088832,
%T A183896 -4503599627370496,0,0,-75557863725914323419136,
%U A183896 -38685626227668133590597632,0,0,-41538374868278621028243970633760768,-85070591730234615865843651857942052864,0
%N A183896 Imaginary part of a (-4,-4) Gaussian integer Somos-4 sequence.
%C A183896 Imaginary part of the Hankel transform of A183893(n) + I*A183894(n).
%C A183896 A183895(n) + I*a(n) is a (-4,-4) Gaussian integer Somos-4 sequence.
%H A183896 G. C. Greubel, <a href="/A183896/b183896.txt">Table of n, a(n) for n = 0..112</a>
%F A183896 a(n) = mod(binomial(n+1,2), 2)*A183895(n).
%t A183896 Table[((-1)^Floor[(n+1)/2] -1)*2^(Floor[n*(n+1)/4] -1), {n,0,30}] (* _G. C. Greubel_, Mar 23 2024 *)
%o A183896 (Magma) [((-1)^Floor((n+1)/2) -1)*2^Floor((n^2+n-4)/4): n in [0..30]]; // _G. C. Greubel_, Mar 23 2024
%o A183896 (SageMath) [((-1)^((n+1)//2) -1)*2^(n*(n+1)//4 -1) for n in range(31)] # _G. C. Greubel_, Mar 23 2024
%Y A183896 Cf. A183893, A183894, A183895.
%K A183896 sign
%O A183896 0,3
%A A183896 _Paul Barry_, Jan 07 2011