Triangle T(n,k) = 10^(n-1) -1 + k*floor(9*10^(n-1)/(n+1)), with 1 <= r <= n, read by rows.

Terms

a(0) =4a(1) =39a(2) =69a(3) =324a(4) =549a(5) =774a(6) =2799a(7) =4599a(8) =6399a(9) =8199a(10) =24999a(11) =39999a(12) =54999a(13) =69999a(14) =84999a(15) =228570a(16) =357141a(17) =485712a(18) =614283a(19) =742854a(20) =871425a(21) =2124999a(22) =3249999a(23) =4374999a(24) =5499999a(25) =6624999a(26) =7749999a(27) =8874999a(28) =19999999a(29) =29999999