Triangular array T(n,k) n,k>=0 is the number of k letter words formed using at most 1a,2b's,3c's,...,n#'s.
A172528
Triangular array T(n,k) n,k>=0 is the number of k letter words formed using at most 1a,2b's,3c's,...,n#'s.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =3a(7) =1a(8) =3a(9) =8a(10) =19a(11) =38a(12) =60a(13) =60a(14) =1a(15) =4a(16) =15a(17) =53a(18) =175a(19) =535a(20) =1490a(21) =3675a(22) =7700a(23) =12600a(24) =12600a(25) =1a(26) =5a(27) =24a(28) =111a(29) =494
External references
- oeis: A172528