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 A188444 #11 Mar 17 2023 14:55:50 %S A188444 1,1,1,-3,-9,-9,-6,10,25,25,15,-21,-49,-49,-28,36,81,81,45,-55,-121, %T A188444 -121,-66,78,169,169,91,-105,-225,-225,-120,136,289,289,153,-171,-361, %U A188444 -361,-190,210,441,441,231,-253,-529,-529,-276,300,625,625,325 %N A188444 Expansion of (1+x)*(1+x+x^2)*(1-x+x^2-4*x+x^4-x^5+x^6)/(1+x^4)^3. %C A188444 a(n+1) is the Hankel transform of A166300(n+3) (diagonal sums of the triangle A100754). %H A188444 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,-3,0,0,0,-3,0,0,0,-1). %F A188444 G.f.: (1+x+x^2-3*x^3-6*x^4-6*x^5-3*x^6+x^7+x^8+x^9)/(1+x^4)^3. %F A188444 a(n) = -3*a(n-4) - 3*a(n-8) - a(n-12). - _Wesley Ivan Hurt_, Mar 17 2023 %K A188444 sign,easy %O A188444 0,4 %A A188444 _Paul Barry_, Mar 31 2011