A111393 - OEIS

%I #8 Dec 26 2014 13:06:46

%S 1,1,2,2,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,

%T 5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,

%U 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7

%N Number of digits in n^3.

%F a(n) = floor( (3*log_10(n)) + 1).

%F a(n) = A055642(n^3). [_R. J. Mathar_, Mar 05 2010]

%e a(10) = 4

%p A055642 :=proc(n) max(1,ilog10(n)+1) ; end proc: A111393 := proc(n) A055642(n^3) ; end proc: seq(A111393(n),n=1..90) ; # _R. J. Mathar_, Mar 05 2010

%t Array[IntegerLength[#^3]&,110] (* _Harvey P. Dale_, Dec 26 2014 *)

%o (PARI) a(n)=if(n==0,1,#digits(n^3)); \\ _Joerg Arndt_, Mar 30 2014

%K base,nonn

%O 1,3

%A Salim Erinc (eryigit(AT)boun.edu.tr), Nov 11 2005

%E Extended by _R. J. Mathar_, Mar 05 2010