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 A367028 #9 Nov 02 2023 10:40:31
%S A367028 1,1,0,-3,-6,2,38,77,-58,-658,-1240,1562,13064,22076,-41710,-279427,
%T A367028 -411418,1114998,6252048,7758726,-29876900,-143956676,-143561972,
%U A367028 802102322,3376515404,2496314012,-21558225312,-80113377828,-37101814188,579611761168
%N A367028 G.f. satisfies A(x) = 1 + x*A(x) - x^2*A(x)^3.
%F A367028 a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(n+k,k) * binomial(n,n-2*k) / (2*k+1).
%o A367028 (PARI) a(n) = sum(k=0, n\2, (-1)^k*binomial(n+k, k)*binomial(n, n-2*k)/(2*k+1));
%Y A367028 Cf. A343773, A367029, A367030.
%Y A367028 Cf. A000108.
%K A367028 sign
%O A367028 0,4
%A A367028 _Seiichi Manyama_, Nov 02 2023