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 A199930 #26 May 20 2025 15:31:11
%S A199930 1,-2,-1,12,-10,-49,112,111,-710,316,3233,-5634,-9505,40592,-1934,
%T A199930 -204897,264664,717295,-2243578,-873336,12543857,-11138050,-50210993,
%U A199930 119318436,108054622,-743719745,372976064,3334358847,-6051013534,-9504084892,42720535345,-4585483266,-212470264817,287622301384
%N A199930 Trisection 0 of A199803.
%C A199930 Also trisection 1 of A199744, negated.
%H A199930 Colin Barker, <a href="/A199930/b199930.txt">Table of n, a(n) for n = 0..1000</a>
%H A199930 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 p. 324.
%H A199930 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-5,1,-1).
%F A199930 From _Colin Barker_, Dec 27 2017: (Start)
%F A199930 G.f.: (1 - x + 2*x^2) / (1 + x + 5*x^2 - x^3 + x^4).
%F A199930 a(n) = -a(n-1) - 5*a(n-2) + a(n-3) - a(n-4) for n>3.
%F A199930 (End)
%t A199930 LinearRecurrence[{-1,-5,1,-1},{1,-2,-1,12},40] (* _Harvey P. Dale_, May 20 2025 *)
%o A199930 (PARI) Vec((1 - x + 2*x^2) / (1 + x + 5*x^2 - x^3 + x^4) + O(x^40)) \\ _Colin Barker_, Dec 27 2017
%Y A199930 Cf. A199744, A199803.
%K A199930 sign,easy
%O A199930 0,2
%A A199930 _N. J. A. Sloane_, Nov 12 2011