47337954326domain: NAppears in sequencesGeneralized ballot numbers (first differences of Motzkin numbers).at n=26A002026Expansion of (1-x)*c(x/(1+x)), where c(x) is the g.f. of the Catalan numbers (A000108).at n=28A105695Expansion of (-2 +x^2 +x -x*sqrt(1-2*x-3*x^2))/(-1 +x -sqrt(1-2*x-3*x^2)).at n=27A244884