Column 2 of triangle A130580.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =13a(5) =30a(6) =76a(7) =211a(8) =638a(9) =2088a(10) =7354a(11) =27731a(12) =111449a(13) =475449a(14) =2145316a(15) =10205714a(16) =51038980a(17) =267623147a(18) =1467786895a(19) =8401550878a(20) =50087295107a(21) =310419697655