A109940 - OEIS

%I #11 Nov 02 2024 09:11:22

%S 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 81,84,87,90,93,96,99,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,98,

%U 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67

%N Largest k-digit multiple of n where k is the number of digits in n.

%H Harvey P. Dale, <a href="/A109940/b109940.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = n * A097326(n). - _Rémy Sigrist_, Nov 01 2024

%t Table[Quotient[10^IntegerLength[n]-1,n]n,{n,60}] (* _Harvey P. Dale_, Oct 16 2011 *)

%o (PARI) a(n) = n * ((10^#digits(n)-1)\n) \\ _Rémy Sigrist_, Nov 01 2024

%Y Cf. A097326.

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_, Jul 19 2005