Triangle read by rows: T(n,k) is the number of 4-ary strings of length n with k indispensable digits, with 0 <= k <= n.

A330509

Triangle read by rows: T(n,k) is the number of 4-ary strings of length n with k indispensable digits, with 0 <= k <= n.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =1a(4) =9a(5) =6a(6) =1a(7) =19a(8) =34a(9) =10a(10) =1a(11) =34a(12) =115a(13) =91a(14) =15a(15) =1a(16) =55a(17) =301a(18) =445a(19) =201a(20) =21a(21) =1a(22) =83a(23) =672a(24) =1582a(25) =1338a(26) =392a(27) =28a(28) =1a(29) =119

External references