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 A283716 #27 Apr 18 2020 02:33:49
%S A283716 3,32,746,19748,531698,14349932,387424586,10460369588,282429602018,
%T A283716 7625597747132,205891133143226,5559060570749828,150094635313776338,
%U A283716 4052555153086085132,109418989131780794666,2954312706551907440468,79766443076876804830658
%N A283716 Row n=3 of A283674.
%H A283716 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (32,-139,108).
%F A283716 G.f.: (3 - 64*x + 139*x^2)/((1 - x)*(1 - 4*x)*(1 - 27*x)).
%F A283716 a(n) = 32*a(n-1) - 139*a(n-2) + 108*a(n-3) for n > 2.
%F A283716 a(n) = 1 + 4^n + 27^n.
%t A283716 Table[1 + 4^n + 27^n, {n, 0, 20}] (* _Bruno Berselli_, Mar 15 2017 *)
%t A283716 CoefficientList[Series[(3 - 64*x + 139*x^2)/((1 - x)*(1 - 4*x)*(1 - 27*x)), {x, 0, 17}], x] (* _Indranil Ghosh_, Mar 15 2017 *)
%o A283716 (PARI) Vec((3 - 64*x + 139*x^2)/((1 - x)*(1 - 4*x)*(1 - 27*x)) + O(x^17)) \\ _Indranil Ghosh_, Mar 15 2017
%o A283716 (PARI) a(n) = 1 + 4^n + 27^n \\ _Indranil Ghosh_, Mar 15 2017
%o A283716 (Python) def A283716(n): return 1 + 4**n + 27**n # _Indranil Ghosh_, Mar 15 2017
%Y A283716 Cf. A283674.
%K A283716 nonn,easy
%O A283716 0,1
%A A283716 _Seiichi Manyama_, Mar 15 2017
%E A283716 Extended by _Bruno Berselli_, Mar 15 2017