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 A344747 #37 Jun 20 2021 03:05:43
%S A344747 0,2,3,16,35,132,343,1136,3195,10012,29183,89256,264355,799892,
%T A344747 2386023,7185376,21501515,64613772,193622863,581305496,1743042675,
%U A344747 5230875652,15689131703,47074385616,141209175835,423655489532,1270910544543,3812843481736,11438306748995
%N A344747 a(n) = (1/6)*(3^n + (-2)^n - 1).
%H A344747 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2,5,-6).
%F A344747 G.f.: x*(2 - x)/((1 - x)*(1 + 2*x)*(1 - 3*x)). - _Andrew Howroyd_, Jun 15 2021
%F A344747 a(n) = A094554(n-1) + 2*A094556(n-1). - _Greg Dresden_, Jun 19 2021
%e A344747 a(4) = (1/6)*(3^4 + (-2)^4 - 1) = (1/6)*(81+16-1) = 16.
%t A344747 LinearRecurrence[{2, 5, -6}, {0, 2, 3}, 30] (* _Greg Dresden_, Jun 19 2021 *)
%Y A344747 Potentially related to A094554, A094555, and A094556 (which have the same recurrence).
%K A344747 nonn,easy
%O A344747 1,2
%A A344747 _Ryan Brooks_, Jun 14 2021