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 A099492 #8 Dec 20 2015 11:29:38
%S A099492 1,0,0,2,-1,-4,5,2,-16,12,27,-56,-3,140,-144,-186,547,-140,-1175,1606,
%T A099492 1120,-5096,2775,9360,-16807,-4584,45664,-38070,-69657,167276,-11347,
%U A099492 -393142,450896,467108,-1595725,586584,3235221,-4905692,-2556720,14641550,-9572661,-25171740,50306641,6820750
%N A099492 A Chebyshev transform of the Padovan-Jacobsthal numbers.
%C A099492 A Chebyshev transform of A052947, which has g.f. 1/(1-x^2-2x^3). The image of G(x) under the Chebyshev transform is (1/(1+x^2))G(x/(1+x^2)).
%H A099492 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,-2,2,-2,0,-1).
%F A099492 G.f.: (1+x^2)^2/(1+2x^2-2x^3+2x^4+x^6); a(n)=-2a(n-2)+2a(n-3)-2a(n-4)-a(n-6); a(n)=sum{k=0..floor(n/2), C(n-k, k)(-1)^k*sum{j=0..floor((n-2k)/2), C(j, n-2k-2j)2^(n-2k-2j)}}.
%t A099492 LinearRecurrence[{0,-2,2,-2,0,-1},{1,0,0,2,-1,-4},50] (* _Harvey P. Dale_, Dec 20 2015 *)
%K A099492 easy,sign
%O A099492 0,4
%A A099492 _Paul Barry_, Oct 19 2004