This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A337127 #50 Sep 23 2020 11:21:47
%S A337127 9,0,0,0,0,0,0,0,0,0,9,81,0,0,0,0,0,0,0,0,9,243,648,0,0,0,0,0,0,0,9,
%T A337127 567,3888,4536,0,0,0,0,0,0,9,1215,16200,45360,27216,0,0,0,0,0,9,2511,
%U A337127 58320,294840,408240,136080,0,0,0,0,9,5103,195048,1587600,3810240,2857680,544320,0,0,0
%N A337127 Table with 10 columns read by rows: T(n, k) is the number of n-digit positive integers with exactly k distinct base 10 digits (0 < k <= 10).
%H A337127 <a href="/index/Di#digits">Index entries for sequences related to digits</a>.
%F A337127 T(n, k) = 9*Pochhammer(11-k, k-1)*n! * [x^n] (exp(x) - 1)^k/k!.
%F A337127 T(n, k) = 9*Pochhammer(11-k, k-1) * [x^n] x^k/Product_{j=1..k} (1-j*x).
%F A337127 T(n, k) = 9*Pochhammer(11-k, k-1)*S2(n, k) where S2(n, k) = A048993(n, k) are the Stirling numbers of the 2nd kind.
%e A337127 The table T(n, k) begins:
%e A337127 9 0 0 0 0 0 0 0 0 0
%e A337127 9 81 0 0 0 0 0 0 0 0
%e A337127 9 243 648 0 0 0 0 0 0 0
%e A337127 9 567 3888 4536 0 0 0 0 0 0
%e A337127 9 1215 16200 45360 27216 0 0 0 0 0
%e A337127 9 2511 58320 294840 408240 136080 0 0 0 0
%e A337127 ...
%t A337127 T[n_,k_]:=9Pochhammer[11-k,k-1]/k!*n!*Coefficient[Series[(Exp[x]-1)^k,{x,0,n}],x,n]; Table[T[n,k],{n,7},{k,10}]//Flatten
%Y A337127 Cf. A010785, A031955, A031962, A031969, A031987, A116670, A171102, A218019, A219743, A220076.
%Y A337127 Cf. A010734, A048993, A052268 (row sums), A073531 (diagonal), A180599 (k = 1), A335843 (k = 2), A337313 (k = 3).
%K A337127 nonn,tabf,base
%O A337127 1,1
%A A337127 _Stefano Spezia_, Aug 17 2020