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a(n) = n - floor( prime(n)/log(prime(n)) ).
1

%I #11 Jun 21 2018 02:00:36

%S -1,0,0,1,1,1,1,2,2,2,2,2,2,3,3,3,3,4,4,4,4,4,5,5,4,5,5,6,6,7,5,6,6,6,

%T 6,6,6,7,7,7,7,8,7,8,8,9,8,7,8,8,9,9,10,9,9,9,9,10,10,11,11,11,10,10,

%U 11,11,10,11,10,11,11,11,11,12,12,12,12,12,13,12,12

%N a(n) = n - floor( prime(n)/log(prime(n)) ).

%H Harry J. Smith, <a href="/A064661/b064661.txt">Table of n, a(n) for n = 1..1000</a>

%t Table[n-Floor[Prime[n]/Log[Prime[n]]],{n,90}] (* _Harvey P. Dale_, Sep 27 2017 *)

%o (PARI) { for (n=1, 1000, write("b064661.txt", n, " ", n - prime(n)\log(prime(n))) ) } \\ _Harry J. Smith_, Sep 21 2009

%Y Cf. A064659-A064663.

%K sign

%O 1,8

%A _N. J. A. Sloane_, Oct 10 2001