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 A144414 #23 Mar 28 2021 04:06:04
%S A144414 1,8,39,166,677,2724,10915,43682,174753,699040,2796191,11184798,
%T A144414 44739229,178956956,715827867,2863311514,11453246105,45812984472,
%U A144414 183251937943,733007751830,2932031007381,11728124029588,46912496118419
%N A144414 a(n) = 2*(4^n - 1)/3 - n.
%H A144414 G. C. Greubel, <a href="/A144414/b144414.txt">Table of n, a(n) for n = 1..1000</a>
%H A144414 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-9,4).
%F A144414 a(n) = A142458(n+1,n).
%F A144414 a(n) = A020988(n) - n. - _R. J. Mathar_, Nov 21 2008
%F A144414 G.f.: x*(1+2*x)/((1-x)^2*(1-4*x)). - _Colin Barker_, Jan 11 2012
%F A144414 a(1)=1, a(2)=8, a(3)=39, a(n) = 6*a(n-1) - 9*a(n-2) + 4*a(n-3). - _Harvey P. Dale_, Mar 17 2015
%F A144414 E.g.f.: (1/3)*(-2 - 3*x + 2*exp(x))*exp(x). - _G. C. Greubel_, Mar 28 2021
%t A144414 Table[2(4^n-1)/3 -n,{n,30}] (* or *) LinearRecurrence[{6,-9,4},{1,8,39},30] (* _Harvey P. Dale_, Mar 17 2015 *)
%o A144414 (Magma) [(2^(2*n+1) -3*n -2)/3: n in [1..50]]; // _G. C. Greubel_, Mar 28 2021
%o A144414 (Sage) [(2^(2*n+1) -3*n -2)/3 for n in (1..50)] # _G. C. Greubel_, Mar 28 2021
%Y A144414 Cf. A142458, A142976, A144380.
%K A144414 nonn
%O A144414 1,2
%A A144414 _Roger L. Bagula_ and _Gary W. Adamson_, Oct 01 2008