A136760 - OEIS

%I #15 Jun 21 2021 13:47:17

%S 1,1,2,6,2,1,8,6,6,6,6,8,1,1,2,4,8,1,3,7,1,4,1,2,7,2,6,2,7,2,8,3,1,4,

%T 1,7,3,1,6,3,1,7,3,1,1,5,3,1,1,5,3,2,1,8,5,3,2,1,1,8,6,4,3,2,2,1,1,1,

%U 1,7,6,6,5,4,4,4,3,3,3,3,3,3,3,3,3,3,4,4,4,5,5,6,7,8,1,1,1,1,2,2

%N a(n) = leading digit of n! in base 9.

%H David A. Corneth, <a href="/A136760/b136760.txt">Table of n, a(n) for n = 0..9999</a>

%e a(10) = 6 as 10! = 6740700_9 which has leading digit 6. - _David A. Corneth_, Jan 15 2021

%t f[n_]:=First[IntegerDigits[n!,9]]; lst={};Do[AppendTo[lst,f[n]],{n,0,2*5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jun 14 2009 *)

%t IntegerDigits[#,9][[1]]&/@(Range[0,100]!) (* _Harvey P. Dale_, Jun 21 2021 *)

%o (PARI) a(n) = digits(n!, 9)[1]; \\ _Michel Marcus_, Jan 27 2015

%Y Cf. A000142, A136696, A136754, A136755, A136756, A136757, A136758, A136759, A008905, A136761, A136762, A136763, A136764, A136765, A136766.

%K base,easy,nonn

%O 0,3

%A _Carl R. White_, Jan 21 2008