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 A080244 #13 Aug 05 2013 07:45:35
%S A080244 1,-2,7,-26,107,-468,2141,-10124,49101,-242934,1221427,-6222838,
%T A080244 32056215,-166690696,873798681,-4612654808,24499322137,-130830894666,
%U A080244 702037771647,-3783431872018,20469182526595,-111133368084892,605312629105205,-3306633429423460,18111655081108453
%N A080244 Signed generalized Fibonacci numbers.
%C A080244 Diagonal sums of triangle A080245
%H A080244 Vincenzo Librandi, <a href="/A080244/b080244.txt">Table of n, a(n) for n = 1..300</a>
%F A080244 G.f.: x*(-1-x+2*x^2+sqrt(1+6*x+x^2))/(2*x*(1+x+x^2-x^3)). - C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004
%F A080244 Conjecture: (n+1)*a(n) +(7*n-2)*a(n-1) +4*(2*n-1)*a(n-2) +6*(n-1)*a(n-3) +(-5*n+1)*a(n-4) +(-n+2)*a(n-5)=0. - _R. J. Mathar_, Nov 24 2012
%p A080244 seq(coeff(convert(series((-1-x+2*x^2+sqrt(1+6*x+x^2))/(2*x*(1+x+x^2-x^3)),x,50),polynom),x,i),i=0..30); (C. Ronaldo)
%t A080244 CoefficientList[Series[(-1 - x + 2 x^2 + Sqrt[1 + 6 x + x^2]) / (2 x (1 + x + x^2 - x^3)), {x, 0, 30}], x] (* _Vincenzo Librandi_, Aug 05 2013 *)
%Y A080244 |a(n)| = A006603.
%K A080244 sign,easy
%O A080244 1,2
%A A080244 _Paul Barry_, Feb 13 2003
%E A080244 More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004
%E A080244 G.f. adapted to the offset by _Vincenzo Librandi_, Aug 05 2013