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 A199744 #19 Jan 05 2025 19:51:39
%S A199744 1,-1,-1,1,2,-1,-4,1,7,0,-12,-3,20,10,-32,-25,49,55,-71,-112,95,216,
%T A199744 -111,-399,94,710,11,-1220,-316,2024,1037,-3233,-2573,4941,5634,-7137,
%U A199744 -11440,9505,22015,-11008,-40592,9073,72112,1934,-123712,-33453,204897,107499,-326675,-264664,498119,577060
%N A199744 G.f.: 1/(1 + x + 2*x^2 + 2*x^3 + x^4).
%H A199744 Michael D. Hirschhorn, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Papers1/43-4/paper43-4-5.pdf">Non-trivial intertwined second-order recurrence relations</a>, Fibonacci Quart. 43 (2005), no. 4, 316-325. See J_n.
%H A199744 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-2,-2,-1).
%F A199744 a(n) = - a(n-1) - 2*a(n-2) - 2*a(n-3) - a(n-4), n > 3. - _Iain Fox_, Dec 25 2017
%t A199744 CoefficientList[Series[1/(1+x+2x^2+2x^3+x^4),{x,0,60}],x] (* or *) LinearRecurrence[ {-1,-2,-2,-1},{1,-1,-1,1},60] (* _Harvey P. Dale_, Nov 19 2020 *)
%o A199744 (PARI) first(n) = Vec(1/(1 + x + 2*x^2 + 2*x^3 + x^4) + O(x^n)) \\ _Iain Fox_, Dec 25 2017
%K A199744 sign,easy
%O A199744 0,5
%A A199744 _N. J. A. Sloane_, Nov 09 2011