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 A109940 #11 Nov 02 2024 09:11:22
%S A109940 9,8,9,8,5,6,7,8,9,90,99,96,91,98,90,96,85,90,95,80,84,88,92,96,75,78,
%T A109940 81,84,87,90,93,96,99,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,98,
%U A109940 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67
%N A109940 Largest k-digit multiple of n where k is the number of digits in n.
%H A109940 Harvey P. Dale, <a href="/A109940/b109940.txt">Table of n, a(n) for n = 1..1000</a>
%F A109940 a(n) = n * A097326(n). - _Rémy Sigrist_, Nov 01 2024
%t A109940 Table[Quotient[10^IntegerLength[n]-1,n]n,{n,60}] (* _Harvey P. Dale_, Oct 16 2011 *)
%o A109940 (PARI) a(n) = n * ((10^#digits(n)-1)\n) \\ _Rémy Sigrist_, Nov 01 2024
%Y A109940 Cf. A097326.
%K A109940 base,easy,nonn
%O A109940 1,1
%A A109940 _Amarnath Murthy_, Jul 19 2005