login
n minus the index of the greatest prime dividing n-th squarefree number: a(n) = n - A243290(n).
6

%I #18 Mar 04 2024 01:35:52

%S 1,1,1,1,3,2,4,3,3,6,8,5,5,10,10,7,11,8,16,9,16,15,19,12,17,20,14,24,

%T 15,21,16,25,17,29,27,26,20,20,28,34,36,23,34,40,25,25,35,43,43,28,38,

%U 29,46,40,45,32,51,47,44,52,36,36,56,37,61,50,39,39,64,58

%N n minus the index of the greatest prime dividing n-th squarefree number: a(n) = n - A243290(n).

%C If A005117(n) <= 2n, or equally, if A243351 is always positive, then this sequence is certainly positive as well.

%H Antti Karttunen, <a href="/A243289/b243289.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = n - A243290(n).

%t With[{t = Table[PrimePi[FactorInteger[k][[-1, 1]]], {k, Select[Range[120], SquareFreeQ]}]}, Range[Length[t]] - t] (* _Amiram Eldar_, Mar 04 2024 *)

%Y Cf. A005117, A006530, A049084, A243290, A243291, A243348, A243349, A243351.

%K nonn

%O 1,5

%A _Antti Karttunen_, Jun 03 2014