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 A136488 #28 Sep 08 2022 08:45:32
%S A136488 1,2,5,10,22,44,92,184,376,752,1520,3040,6112,12224,24512,49024,98176,
%T A136488 196352,392960,785920,1572352,3144704,6290432,12580864,25163776,
%U A136488 50327552,100659200,201318400,402644992,805289984,1610596352,3221192704,6442418176,12884836352
%N A136488 a(n) = 2^n - A005418(n).
%H A136488 Colin Barker, <a href="/A136488/b136488.txt">Table of n, a(n) for n = 1..1000</a>
%H A136488 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2,2,-4).
%F A136488 a(n) = 2^n - A005418(n). Sum of (n-1)-th row terms of triangle A136482.
%F A136488 G.f.: x*(1 - x^2)/(1 - 2*x - 2*x^2 + 4*x^3). - _Michael De Vlieger_, Sep 23 2016
%F A136488 From _Colin Barker_, Sep 23 2016: (Start)
%F A136488 a(n) = 3*2^(n-2)-2^(n/2-1) for n even.
%F A136488 a(n) = 3*2^(n-2)-2^((n-3)/2) for n odd.
%F A136488 (End)
%F A136488 a(n) = A135098(n-1) for n >= 1. - _Georg Fischer_, Nov 02 2018
%e A136488 a(5) = 22 = 2^5 - A005418(5) = 32 - 10.
%e A136488 a(5) = 22 = sum of row 5 terms of triangle A136482 = (1 + 6 + 8 + 6 + 1).
%t A136488 Table[2^n - (2^(n - 2) + 2^(Floor[n/2] - 1)), {n, 40}] (* after _Harvey P. Dale_ at A005418, or *)
%t A136488 CoefficientList[Series[(1 - x^2)/(1 - 2 x - 2 x^2 + 4 x^3), {x, 0, 40}], x] (* _Michael De Vlieger_, Sep 23 2016 *)
%o A136488 (PARI) Vec(x*(1-x)*(1+x)/((1-2*x)*(1-2*x^2)) + O(x^40)) \\ _Colin Barker_, Sep 23 2016
%o A136488 (Magma) [2^n - (2^(n - 2) + 2^(Floor(n/2) - 1)): n in [1..40]]; // _G. C. Greubel_, Nov 02 2018
%Y A136488 Cf. A005418, A135098, A136482.
%K A136488 nonn,easy
%O A136488 1,2
%A A136488 _Gary W. Adamson_, Jan 01 2008
%E A136488 More terms from _Colin Barker_, Mar 19 2013
%E A136488 Missing a(4) added by _Michael De Vlieger_, Sep 23 2016