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 A178115 #11 Jun 13 2015 00:53:37 %S A178115 1,-2,-2,5,5,-13,-13,34,34,-89,-89,233,233,-610,-610,1597,1597,-4181, %T A178115 -4181,10946,10946,-28657,-28657,75025,75025,-196418,-196418,514229, %U A178115 514229,-1346269,-1346269,3524578,3524578,-9227465,-9227465,24157817 %N A178115 a(n)=(-1)^C(n+1,2)*(F(n+1)*(1+(-1)^n)/2+F(n+2)*(1-(-1)^n)/2). %C A178115 Duplicated A001519 with alternating signs. %C A178115 Hankel transform of A178113. Hankel transform of A178114. %H A178115 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,-3,0,-1). %F A178115 G.f.: (1-2x+x^2-x^3)/(1+3x^2+x^4). %F A178115 |a(n)| = A094967(n+1). - _R. J. Mathar_, Dec 10 2010 %o A178115 (PARI) Vec((1-2*x+x^2-x^3)/(1+3*x^2+x^4) + O(x^50)) \\ _Michel Marcus_, Dec 03 2014 %K A178115 easy,sign %O A178115 0,2 %A A178115 _Paul Barry_, May 20 2010