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 A093380 #7 Dec 18 2022 13:41:55
%S A093380 1,6,14,22,46,86,174,342,686,1366,2734,5462,10926,21846,43694,87382,
%T A093380 174766,349526,699054,1398102,2796206,5592406,11184814,22369622,
%U A093380 44739246,89478486,178956974,357913942,715827886,1431655766,2863311534
%N A093380 Expansion of (1+4x+x^2-10x^3)/((1-x)(1-x-2x^2)).
%C A093380 Second binomial transform is A093381.
%H A093380 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,-2)
%F A093380 a(n)=2-5*0^n+4(2*2^n/3+(-1)^n/3); a(n)=2-5*0^n+4*A001045(n+1).
%t A093380 Block[{$RecursionLimit=1000}, CoefficientList[Series[(1+4x+x^2-10x^3)/((1-x)(1-x-2x^2)),{x,0,40}],x]] (* or *) LinearRecurrence[{2,1,-2},{1,6,14,22},40] (* _Harvey P. Dale_, Dec 18 2022 *)
%K A093380 easy,nonn
%O A093380 0,2
%A A093380 _Paul Barry_, Apr 28 2004