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 A110394 #9 Mar 13 2024 19:45:24
%S A110394 1,16,249,3000,34995,390024,4269825,45841392,487427463,5125725360,
%T A110394 53617021029,556595747640,5764255280667,59300426070648,
%U A110394 610493608940265,6232102256955744,64054261631752335,647023290628457952
%N A110394 a(1) = 1; a(n) = n times (9's complement of a(n-1)).
%C A110394 a(1)=1; a(n)=n*[99...9 - a(n-1)] for n>1 (99...9 and a[n-1] have the same number of digits). - _Emeric Deutsch_, Jul 31 2005
%H A110394 Alois P. Heinz, <a href="/A110394/b110394.txt">Table of n, a(n) for n = 1..400</a>
%e A110394 a(4) = 4 times 9's complement of a(3) = 4*(999-249) = 3000.
%p A110394 s:=proc(m) nops(convert(m,base,10)) end: a[1]:=1: for n from 2 to 21 do a[n]:=n*(10^s(a[n-1])-1-a[n-1]) od: seq(a[n],n=1..21); # _Emeric Deutsch_, Jul 31 2005
%p A110394 # second Maple program:
%p A110394 a:= proc(n) option remember; `if`(n=1, 1,
%p A110394 n*(p-> 10^length(p)-1-p)(a(n-1)))
%p A110394 end:
%p A110394 seq(a(n), n=1..30); # _Alois P. Heinz_, Sep 22 2015
%t A110394 nxt[{n_,a_}]:={n+1,(n+1)(FromDigits[PadRight[{},IntegerLength[a],9]]-a)}; NestList[nxt,{1,1},20][[;;,2]] (* _Harvey P. Dale_, Mar 13 2024 *)
%K A110394 base,easy,nonn
%O A110394 1,2
%A A110394 _Amarnath Murthy_, Jul 29 2005
%E A110394 More terms from _Emeric Deutsch_, Jul 31 2005