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 A147975 #17 Apr 11 2024 03:52:26
%S A147975 -2,-2,2,28,158,748,3302,14068,58718,241948,988502,4015108,16241678,
%T A147975 65506348,263636102,1059360148,4251855038,17050597948,68331794102,
%U A147975 273715121188,1096023794798,4387584060748,17560800790502,70274592610228
%N A147975 a(n) = 4^n-3^n-2^n-1.
%H A147975 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (10,-35,50,-24).
%F A147975 G.f.: 2*x*(19*x^3-24*x^2+9*x-1)/((x-1)*(2*x-1)*(3*x-1)*(4*x-1)). - _Colin Barker_, Oct 29 2012
%t A147975 lst={};Do[p=4^n-3^n-2^n-1^n;AppendTo[lst,p],{n,0,5!}];lst
%t A147975 LinearRecurrence[{10,-35,50,-24},{-2,-2,2,28},40] (* _Harvey P. Dale_, Nov 08 2016 *)
%o A147975 (PARI) a(n)=4^n-3^n-2^n-1 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A147975 Cf. A147976, A147977, A147978, A147979.
%K A147975 sign,easy
%O A147975 1,1
%A A147975 _Vladimir Joseph Stephan Orlovsky_, Nov 18 2008