[ exp(1/19)*n! ].

Terms

a(0) =1a(1) =2a(2) =6a(3) =25a(4) =126a(5) =758a(6) =5312a(7) =42498a(8) =382490a(9) =3824904a(10) =42073953a(11) =504887441a(12) =6563536741a(13) =91889514383