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 A098276 #18 Sep 29 2013 21:16:48
%S A098276 1,0,2,0,72,-320,3600,-32256,344960,-3926016,48625920,-648243200,
%T A098276 9270125568,-141579509760,2300668418048,-39642283376640,
%U A098276 722055883161600,-13863472939925504,279868860012625920
%N A098276 Difference between the number of even reduced Latin rectangles of size 3 X n and the number of odd ones.
%H A098276 Vincenzo Librandi, <a href="/A098276/b098276.txt">Table of n, a(n) for n = 1..200</a>
%H A098276 J. Zeng, <a href="http://math.univ-lyon1.fr/homes-www/zeng/public_html/paper/publication.html">The generating function for the difference in even and odd three-line latin rectangles</a>, Ann. Sci. Math. Quebec 20/1 (1996) 105-108. [<a href="http://www.labmath.uqam.ca/~annales/volumes/20-1/PDF/105-108.pdf">alternate link</a>]
%F A098276 E.g.f.: x + [(1-x)^2/(1+x)+x/(1+x)^2] * exp(2x). - corrected by _Vaclav Kotesovec_, Sep 29 2013
%F A098276 a(n) ~ n! * (-1)^(n+1) * n * exp(-2). - _Vaclav Kotesovec_, Sep 29 2013
%t A098276 Rest[CoefficientList[Series[x + ((1-x)^2/(1+x)+x/(1+x)^2)*E^(2*x), {x, 0, 20}], x]* Range[0, 20]!] (* _Vaclav Kotesovec_, Sep 29 2013 *)
%o A098276 (PARI) a(n)=polcoeff(serlaplace(exp(2*x)*((1-x)^2/(1+x)+x/(1+x)^2)),n)
%o A098276 (PARI) a(n)=(-1)^(n-1)*(n-2)*n!/2*polcoeff(Ser(exp(2*(atanh(x)-x))),n)
%Y A098276 Cf. A000186.
%K A098276 sign,easy
%O A098276 1,3
%A A098276 _Ralf Stephan_, Sep 06 2004