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 A288780 #32 Jun 22 2017 14:38:54
%S A288780 0,0,2,9,36,165,918,6111,47304,416097,4091130,44417043,527456556,
%T A288780 6798432069,94499679582,1408924024695,22425642181008,379514672913321,
%U A288780 6804212771165634,128827325000617947,2568509718703606260,53787877376348226573,1180349932648067726886
%N A288780 Zero together with the row sums of A288778.
%C A288780 For n >= 2, a(n) is the number of numbers in base n with consecutive digits after reordering.
%C A288780 a(10) = 4091130 is also the number of positive terms in the finite sequence A215014, hence a(10) + 1 = 4091131 is the total number of terms in that sequence.
%H A288780 Alois P. Heinz, <a href="/A288780/b288780.txt">Table of n, a(n) for n = 0..450</a>
%p A288780 a:= proc(n) option remember; `if`(n<3, n*(n-1),
%p A288780 n*(a(n-1)*n/(n-1)-a(n-2)*(n-1)/(n-2)))
%p A288780 end:
%p A288780 seq(a(n), n=0..25); # _Alois P. Heinz_, Jun 16 2017
%t A288780 {0}~Join~Map[Total, Table[(n - k + 1) k! - (k - 1)!, {n, 22}, {k, n}]] (* _Michael De Vlieger_, Jun 21 2017 *)
%Y A288780 Cf. A215014, A288777, A288778.
%K A288780 nonn
%O A288780 0,3
%A A288780 _Omar E. Pol_, Jun 15 2017
%E A288780 More terms from _Alois P. Heinz_, Jun 16 2017