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 A376585 #12 Sep 30 2024 10:21:33
%S A376585 1,2,6,24,104,448,1888,7808,31872,129024,519680,2086912,8366080,
%T A376585 33505280,134111232,536641536,2146992128,8588886016,34357510144,
%U A376585 137434234880,549745852416,2199002284032,8796048982016,35184279814144,140737295417344,562949550768128,2251798974824448
%N A376585 a(n) = 2^(2*n - 1) - 2^(n - 1)*(n - 1).
%H A376585 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (8,-20,16).
%F A376585 a(n) = [x^n] (-10*x^2 + 6*x - 1)/((2*x - 1)^2*(4*x - 1)).
%F A376585 a(n) = ((24 - 8*n)*a(n - 2) + (6*n - 22)*a(n - 1)) / (n - 4) for n >= 5.
%p A376585 A376585 := n -> 2^(2*n - 1) - 2^(n - 1)*(n - 1):
%t A376585 LinearRecurrence[{8, -20, 16}, {1, 2, 6}, 27] (* _Hugo Pfoertner_, Sep 29 2024 *)
%Y A376585 Cf. A020522.
%K A376585 nonn,easy
%O A376585 0,2
%A A376585 _Peter Luschny_, Sep 29 2024