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 A152167 #19 Apr 09 2024 08:09:06
%S A152167 1,-3,6,-15,33,-78,177,-411,942,-2175,5001,-11526,26529,-61107,140694,
%T A152167 -324015,746097,-1718142,3956433,-9110859,20980158,-48312735,
%U A152167 111253209,-256191414,589951041,-1358525283,3128378406,-7203954255,16589089473
%N A152167 a(n)=-a(n-1)+3*a(n-2), n>1 ; a(0)=1, a(1)=-3 .
%H A152167 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (-1,3).
%F A152167 G.f.: (1-2*x)/(1+x-3*x^2).
%F A152167 a(n) = (-1)^n*A105476(n+1).
%F A152167 a(n) = Sum{k=0..n} A147703(n,k)*(-4)^k.
%t A152167 LinearRecurrence[{-1,3},{1,-3},30] (* _Harvey P. Dale_, Dec 24 2013 *)
%o A152167 (PARI) Vec((1-2*x)/(1+x-3*x^2)+O(x^99)) \\ _Charles R Greathouse IV_, Jan 11 2012
%Y A152167 Cf. A105476, A147703.
%K A152167 sign,easy
%O A152167 0,2
%A A152167 _Philippe Deléham_, Nov 27 2008
%E A152167 a(19) corrected by _Charles R Greathouse IV_, Jan 11 2012