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 A118409 #5 Dec 23 2024 10:19:24
%S A118409 1,1,3,5,5,7,11,17,21,27,47,73,85,111,187,289,341,443,751,1161,1365,
%T A118409 1775,3003,4641,5461,7099,12015,18569,21845,28399,48059,74273,87381,
%U A118409 113595,192239,297097,349525,454383,768955,1188385,1398101,1817531
%N A118409 Unsigned row sums of triangle A118407.
%H A118409 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 0, 3, -3, 0, 0, 4, -4).
%F A118409 G.f.: (1+2*x^2+2*x^3-3*x^4+2*x^5-2*x^6)/(1+x^4)/(1-4*x^4)/(1-x).
%o A118409 (PARI) {a(n)=polcoeff((1+2*x^2+2*x^3-3*x^4+2*x^5-2*x^6)/(1+x^4)/(1-4*x^4)/(1-x+x*O(x^n)),n)}
%Y A118409 Cf. A118407 (triangle), A118408 (row sums).
%K A118409 nonn
%O A118409 0,3
%A A118409 _Paul D. Hanna_, Apr 27 2006