G.f. satisfies A(x) = (1 + x/A(x))/(1 - x)^3.

Terms

a(0) =1a(1) =4a(2) =5a(3) =15a(4) =-5a(5) =111a(6) =-402a(7) =2172a(8) =-10892a(9) =57362a(10) =-305756a(11) =1656560a(12) =-9083341a(13) =50328219a(14) =-281324174a(15) =1584578882a(16) =-8984740332a(17) =51242962422a(18) =-293772467974