54793282domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/4)} binomial(n+2*k,n-4*k).at n=23A373906Expansion of (1 + x^2 - x^3)/((1 + x^2 - x^3)^2 - 4*x^2).at n=33A376726Expansion of 1 / ((1-x)^4 - x^6).at n=30A392542