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 A190968 #28 Dec 23 2023 09:42:47
%S A190968 0,1,4,6,-16,-124,-336,-104,2944,12816,21824,-40864,-381696,-1118144,
%T A190968 -655616,8558976,40792064,77578496,-97606656,-1166211584,-3688779776,
%U A190968 -3093003264,24515784704,128993171456,270814838784,-206672359424,-3534837825536,-12072627707904
%N A190968 a(n) = 4*a(n-1) - 10*a(n-2), with a(0)=0, a(1)=1.
%H A190968 Michael De Vlieger, <a href="/A190968/b190968.txt">Table of n, a(n) for n = 0..2000</a>
%H A190968 Beata Bajorska-Harapińska, Barbara Smoleń, and Roman Wituła, <a href="https://doi.org/10.1007/s00006-019-0969-9">On Quaternion Equivalents for Quasi-Fibonacci Numbers, Shortly Quaternaccis</a>, Advances in Applied Clifford Algebras (2019) Vol. 29, 54.
%H A190968 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,-10).
%F A190968 G.f.: x/(1 - 4*x + 10*x^2). - _Philippe Deléham_, Oct 12 2011
%t A190968 LinearRecurrence[{4,-10}, {0,1}, 50]
%Y A190968 Cf. A190958 (index to generalized Fibonacci sequences).
%K A190968 sign
%O A190968 0,3
%A A190968 _Vladimir Joseph Stephan Orlovsky_, May 24 2011