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Difference between the n-th squarefree number and the index of its largest prime factor.
3

%I #9 Mar 04 2024 01:38:42

%S 1,1,1,2,4,3,7,6,7,10,12,10,11,17,17,14,20,19,27,20,28,27,31,25,30,33,

%T 28,38,29,37,32,44,37,50,49,48,42,43,51,59,61,48,60,66,51,52,62,72,72,

%U 57,69,60,78,72,77,65,85,82,79,87,72,75,95,76,101,90,79,80,105

%N Difference between the n-th squarefree number and the index of its largest prime factor.

%C Different from A243289. A243348 gives the difference a(n) - A243289(n).

%H Antti Karttunen, <a href="/A243349/b243349.txt">Table of n, a(n) for n = 1..10001</a>

%F a(n) = A243291(A005117(n)).

%F a(n) = A005117(n) - A061395(A005117(n)).

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

%o (Scheme) (define (A243349 n) (A243291 (A005117 n)))

%Y Cf. A005117, A243289, A243290, A243291, A243348.

%K nonn

%O 1,4

%A _Antti Karttunen_, Jun 04 2014