login
Denominator of (n-th noncomposite/n).
2

%I #18 Jun 08 2020 04:46:09

%S 1,1,1,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,

%T 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,

%U 50

%N Denominator of (n-th noncomposite/n).

%C Denominator of (A008578(n)/n).

%F a(1) = a(2) = a(3) = 1, a(n) = n for n >= 4.

%t Module[{nn=300,c,len},c=Select[Range[nn],!CompositeQ[#]&];len=Length[ c]; #[[1]]/#[[2]]&/@Thread[{c,Range[len]}]]//Denominator (* or *) Join[{1,1,1}, Range[ 4,60]] (* _Harvey P. Dale_, Feb 08 2020 *)

%Y Cf. A008578.

%K nonn,easy

%O 1,4

%A _Jaroslav Krizek_, Dec 11 2009

%E Corrected by _Jaroslav Krizek_, Dec 16 2009