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 A138208 #7 Sep 26 2024 23:16:44
%S A138208 1,1,-1,4,-28,281,-3684,59731,-1154936,25950691,-664613080,
%T A138208 19112126640,-609797430996,21378439099625,-816913146902756,
%U A138208 33793354034365895,-1504592807223959688,71739597692510725317,-3647111535920547933017
%N A138208 G.f.: A(x) = 1 + x*(1 + x*(1 + x*(...(1 + x*(...)^(-2n+1))...)^-5)^-3)^-1.
%e A138208 G.f.: A(x)=1+x/B(x), B(x)=1+x/C(x)^3, C(x)=1+x/D(x)^5, D(x)=1+x/E(x)^7, ...
%e A138208 where A(x),B(x),C(x),... are the g.f. of the sequences given below.
%e A138208 A=[1,1,-1,4,-28,281,-3684,59731,-1154936,25950691,...];
%e A138208 B=[1,1,-3,21,-220,3015,-50721,1009311,-23180763,603647340,...];
%e A138208 C=[1,1,-5,50,-700,12250,-254086,6060285,-163013950,4877935870,...];
%e A138208 D=[1,1,-7,91,-1596,34062,-843003,23549442,-730039689,24824392005,...];
%e A138208 E=[1,1,-9,144,-3036,76527,-2204136,70735467,-2490112548,95152481622,...];
%e A138208 F=[1,1,-11,209,-5148,149721,-4923061,178674925,-7052351735,...]; ...
%o A138208 (PARI) {a(n)=my(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x/A^(2*(n-j)-1)); polcoeff(A, n)}
%Y A138208 Cf. A121587, A138211, A138210, A138209.
%K A138208 sign
%O A138208 0,4
%A A138208 _Paul D. Hanna_, Mar 06 2008