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 A078059 #8 Mar 19 2025 09:57:10 %S A078059 1,-3,7,-19,51,-135,359,-955,2539,-6751,17951,-47731,126915,-337463, %T A078059 897303,-2385899,6344027,-16868559,44852943,-119262499,317115059, %U A078059 -843198503,2242037063,-5961502747,15851439563,-42148455999,112071357055,-297994049235,792356367523,-2106849498391 %N A078059 Expansion of (1-x)/(1+2*x-x^2+2*x^3). %H A078059 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,1,-2). %F A078059 a(0) = 1, a(1) = -3, a(2) = 7, a(n) = -2*a(n-1) + a(n-2) - 2*a(n-3) for n > 2. - _Jinyuan Wang_, Apr 07 2020 %F A078059 a(n) = A077987(n)-A077987(n-1). - _R. J. Mathar_, Mar 19 2025 %o A078059 (PARI) Vec((1-x)/(1+2*x-x^2+2*x^3) + O(x^50)) \\ _Jinyuan Wang_, Apr 07 2020 %K A078059 sign,easy %O A078059 0,2 %A A078059 _N. J. A. Sloane_, Nov 17 2002