184414199430domain: NAppears in sequencesExpansion of g.f.: (1-2*x)*(1-4*x+x^2)/((1-x)*(1-3*x)*(1-4*x)).at n=20A087433Constant term of the reduction of the polynomial p(n,x)=(1/2)((x+2)^n+(x-2)^n) by x^2->x+2.at n=20A192355