A110453 - OEIS

%I #17 Sep 05 2024 12:21:31

%S 362880,362880,90720,10080,630,25,0,0,0

%N Floor[Product of all k-digit numbers starting from n divided by product of all k-digit numbers less than n] where k is the number of digits in n.

%C That is, a(n) = floor(n*(n+1)*...*(10^k-1)/R), where k is the number of digits in n and R = (n-1)*(n-2)*...*(10^(k-1)+1)*(10^(k-1)).

%C There is no room for the next term, which is 152 digits long. - _David Wasserman_, Dec 01 2008

%H Jason Yuen, <a href="/A110453/b110453.txt">Table of n, a(n) for n = 1..99</a>

%e a(5) = 5*6*7*8*9/(4!) = 630.

%o (PARI) a(n) = my(k=#digits(n)); floor(prod(i=n, 10^k-1, i)/prod(i=10^(k-1), n-1, i)); \\ _Michel Marcus_, Sep 05 2024

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_, Aug 04 2005