E.g.f.: exp( x/(1 - x - x^2) ).

Terms

a(0) =1a(1) =1a(2) =3a(3) =19a(4) =145a(5) =1401a(6) =16051a(7) =213403a(8) =3223809a(9) =54514225a(10) =1019601091a(11) =20890209891a(12) =465156779473