Column 2 of triangle A108267.

Terms

a(0) =1a(1) =31a(2) =381a(3) =3431a(4) =26769a(5) =193705a(6) =1343521a(7) =9091270a(8) =60632419a(9) =401001030a(10) =2639871326a(11) =17339260251a(12) =113792427233a(13) =746807661549