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 A238187 #22 Sep 08 2022 08:46:07
%S A238187 4,5,5,5,9,25,65,145,289,545,1025,1985,3969,8065,16385,33025,66049,
%T A238187 131585,262145,523265,1046529,2095105,4194305,8392705,16785409,
%U A238187 33562625,67108865,134201345,268402689,536838145,1073741825,2147549185,4295098369,8590065665
%N A238187 Gaussian norm of 1+(1+i)^n.
%H A238187 Vincenzo Librandi, <a href="/A238187/b238187.txt">Table of n, a(n) for n = 0..1000</a>
%F A238187 G.f.: -(10*x^3-20*x^2+15*x-4)/((x-1)*(2*x-1)*(2*x^2-2*x+1)). [_Joerg Arndt_, Feb 20 2014]
%F A238187 a(n) = 2^n + (1+i)^n + (1-i)^n + 1. [_Bruno Berselli_, Feb 20 2014]
%p A238187 seq(GInorm(1+(1+I)**n),n=0..33);
%t A238187 Table[Norm[{1 + (1 + I)^n}]^2, {n, 0, 40}] (* _Bruno Berselli_, Feb 20 2014 *)
%t A238187 CoefficientList[Series[-(10 x^3 - 20 x^2 + 15 x - 4)/((x - 1) (2 x - 1) (2 x^2 - 2 x + 1)), {x, 0, 40}], x] (* _Vincenzo Librandi_, Feb 21 2014 *)
%o A238187 (PARI) a(n) = norml2(1+(1+I)^n); \\ _Michel Marcus_, Feb 19 2014
%o A238187 (Magma) [Floor(2^n+(1+Sqrt(-1))^n+(1-Sqrt(-1))^n+1): n in [0..40]]; // _Vincenzo Librandi_, Feb 21 2014
%K A238187 nonn,easy
%O A238187 0,1
%A A238187 _Cristóbal Camarero_, Feb 19 2014