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 A173344 #25 Mar 17 2024 14:06:27
%S A173344 0,1,0,-2,-3,0,8,13,0,-34,-55,0,144,233,0,-610,-987,0,2584,4181,0,
%T A173344 -10946,-17711,0,46368,75025,0,-196418,-317811,0,832040,1346269,0,
%U A173344 -3524578,-5702887,0,14930352,24157817,0,-63245986,-102334155,0
%N A173344 a(n+4) = a(n+3) - 2*a(n+2) - a(n+1) - a(n), starting with (0, 1, 0, -2).
%C A173344 See A173343. A151889 gives a nonnegative version without zeros. (a(n)) = kibseq(X) with X = -0.25'i + 0.5'j + 0.5'k + 0.25'i + j' + 0.5k' - 0.25ii - 0.25'jj' - 0.25'kk' + 0.5'ij' + 0.5'ik' - 0.5'ji' -0.25'jk' + 0.25'kj' + 0.25'ee' (see Munafo link for definitions).
%H A173344 C. Dement, <a href="http://fumba.eu/sitelayout/Floretion.html">Online Floretion Multiplier</a> [broken link]
%H A173344 R. Munafo, <a href="http://www.mrob.com/pub/math/seq-floretion.html">Sequences Related to Floretions</a>
%H A173344 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,-2,-1,-1).
%F A173344 G.f.: x*(1-x)/(x^4+x^3+2*x^2-x+1).
%F A173344 a(n) = A275858(n-1)-A275858(n-2). - _R. J. Mathar_, Mar 23 2023
%t A173344 CoefficientList[Series[(x-x^2)/(1-x+2 x^2+x^3+x^4),{x,0,50}],x] (* _Harvey P. Dale_, Apr 01 2011 *)
%o A173344 (PARI) concat(0, Vec((x-x^2)/(x^4+x^3+2*x^2-x+1) + O(x^50))) \\ _Michel Marcus_, Oct 29 2022
%Y A173344 Cf. A151889, A173343, A275858.
%K A173344 easy,sign
%O A173344 0,4
%A A173344 _Creighton Dement_, Feb 16 2010
%E A173344 Name edited by _Michel Marcus_, Oct 29 2022