E.g.f.: exp( (x * (1 + x) * exp(x) - sinh(x)) / 4 ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =7a(5) =26a(6) =124a(7) =628a(8) =3565a(9) =22096a(10) =149176a(11) =1080868a(12) =8372543a(13) =68957268a(14) =601351748a(15) =5528967282a(16) =53416626441a(17) =540682811424