9153665985domain: NAppears in sequencesa(1)=1; a(n)=sum(u=1,n-1,sum(v=1,u,sum(w=1,v,sum(x=1, w,sum(y=1,x,a(y)))))).at n=17A079675A quadrisection of 1/(1-x-x^5).at n=21A099235Number of n-step one-sided prudent walks, avoiding exactly two consecutive west steps (can have three or more west steps).at n=27A190525