Third column of second-order Eulerian triangle A008517 divided by 2.

Terms

a(0) =3a(1) =29a(2) =164a(3) =726a(4) =2805a(5) =9975a(6) =33630a(7) =109424a(8) =347519a(9) =1085313a(10) =3349848a(11) =10253994a(12) =31203945a(13) =94561643a(14) =285716018a(15) =861472836a(16) =2593592883a(17) =7800176565a(18) =23441423340a(19) =70410252350a(20) =211411111133a(21) =634610819679