Column k=5 of triangle A257673.

Terms

a(0) =1a(1) =15a(2) =120a(3) =695a(4) =3285a(5) =13473a(6) =49730a(7) =169115a(8) =538440a(9) =1623660a(10) =4677121a(11) =12955065a(12) =34682730a(13) =90113220a(14) =227992870a(15) =563267203a(16) =1361992935a(17) =3229643480a(18) =7522847555a(19) =17237982025a(20) =38905739524a(21) =86585024910a(22) =190193593830a(23) =412712252535a(24) =885382820550