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 A138232 #10 Apr 23 2022 13:50:46
%S A138232 1,0,0,1,-2,2,-4,2,-4,0,0,-4,8,-8,16,-8,16,0,0,16,-32,32,-64,32,-64,0,
%T A138232 0,-64,128,-128,256,-128,256,0,0,256,-512,512,-1024,512,-1024,0,0,
%U A138232 -1024,2048,-2048,4096,-2048,4096,0,0,4096,-8192,8192,-16384,8192,-16384,0,0,-16384,32768
%N A138232 First differences of A138231.
%C A138232 The sequence contains 2 copies of 1 and 3 copies of the higher powers 2^j (up to sign).
%H A138232 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0, 2, 0, -2).
%F A138232 a(n) = 2a(n-2)-2a(n-4). a(n) = -4a(n-8).
%F A138232 a(2n) = (-1)^(n+1)*A090132(n). a(2n+1) = A009545(n).
%F A138232 O.g.f.: (x-1)(x^2-x-1)/(1-2x^2+2x^4). - _R. J. Mathar_, Jul 08 2008
%t A138232 LinearRecurrence[{0,2,0,-2},{1,0,0,1},70] (* _Harvey P. Dale_, Apr 23 2022 *)
%Y A138232 Cf. A000079, A131577.
%K A138232 sign
%O A138232 0,5
%A A138232 _Paul Curtz_, May 05 2008
%E A138232 Edited by _R. J. Mathar_, Jul 08 2008