a(n) = T(7,n), array T given by A048505.

Terms

a(0) =1a(1) =65a(2) =210a(3) =536a(4) =1264a(5) =2880a(6) =6448a(7) =14288a(8) =31440a(9) =68816a(10) =149968a(11) =325584a(12) =704464a(13) =1519568a(14) =3268560a(15) =7012304a(16) =15007696a(17) =32047056a(18) =68288464a(19) =145227728a(20) =308281296a(21) =653262800a(22) =1382023120a(23) =2919235536a(24) =6157238224a(25) =12968787920a(26) =27279753168a(27) =57310969808a(28) =120259084240