A082513 - OEIS

%I #4 Oct 15 2013 22:31:56

%S -1,-1,0,-1,1,-1,2,0,1,0,3,-1,4,2,2,1,5,1,6,2,4,4,7,1,6,5,5,3,8,2,9,5,

%T 7,7,7,2,10,8,8,4,11,5,12,8,8,10,13,5,12,9,11,9,14,8,12,8,12,12,15,5,

%U 16,14,12,11,14,10,17,13,15,11,18,8,19,17,15,15,17,13,20,12,17,18,21,11,19,19,19,15,22,12,20,18,20,20,20,12,23,19,19,16

%N a(n)=A000720(n)-A000005(n).

%t Table[ -DivisorSigma[0, w]+PrimePi[w], {w, 1, 128}]

%Y Cf. A000010, A000005, A000720, A073757, A037228, A063070, A045763.

%K easy,sign

%O 1,7

%A _Labos Elemer_, Apr 29 2003