567019562429domain: NAppears in sequencesGeneralized Catalan numbers A(x)^2 -(1+x)^2*A(x) +x*(2+x+x^2) =0.at n=27A025242Expansion of (1 + x^2 - sqrt( 1 - 4*x + 2*x^2 + x^4)) / (2*x) in powers of x.at n=27A082582Number of Dyck paths of semilength n with no DDUU.at n=26A086581