O.g.f.: Sum_{n>=0} (1+n^2*x)^n * x^n/n! * exp(-(1+n^2*x)*x).

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =7a(5) =18a(6) =96a(7) =260a(8) =1851a(9) =5270a(10) =46515a(11) =137942a(12) =1447202a(13) =4433772a(14) =53787706a(15) =169169912a(16) =2326986783a(17) =7477418982a(18) =114916173009a(19) =375898894514