%I A063070
%S A063070 0,1,0,1,2,2,4,0,3,0,8,2,10,2,4,3,14,0,16,2,8,6,20,0,17,8,14,6,26,0,28,
               10,16,12,
%T A063070 20,3,34,14,20,8,38,4,40,14,18,18,44,6,39,14,28,18,50,10,36,16,32,24,56,
               4,58,26,30,25,
%U A063070 44,12,64,26,40,16,68,12,70,32,34,30,56,16,76,22,49,36,80,12,60,38,52,
               32,86,12,68,38
%V A063070 0,-1,0,-1,2,-2,4,0,3,0,8,-2,10,2,4,3,14,0,16,2,8,6,20,0,17,8,14,6,26,
               0,28,10,16,12,
%W A063070 20,3,34,14,20,8,38,4,40,14,18,18,44,6,39,14,28,18,50,10,36,16,32,24,56,
               4,58,26,30,25,
%X A063070 44,12,64,26,40,16,68,12,70,32,34,30,56,16,76,22,49,36,80,12,60,38,52,
               32,86,12,68,38
%N A063070 Phi(n)-d(n), where d(n) is the number of divisors function (A00005).
%C A063070 It is known that a(n) >= 1 for n >= 31.
%D A063070 D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, p. 11.
%H A063070 T. D. Noe, <a href="b063070.txt">Table of n, a(n) for n=1..1000</a>
%o A063070 (PARI) j=[]; for(n=1,150,j=concat(j,eulerphi(n)-(numdiv(n)))); j
%o A063070 (PARI) { for (n=1, 1000, write("b063070.txt", n, " ", eulerphi(n) - numdiv(n)) 
               ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 16 2009]
%Y A063070 Cf. A000010, A000005. A020488 gives n such that a(n) = 0.
%Y A063070 Sequence in context: A088251 A140839 A127528 this_sequence A049802 A129240 
               A127786
%Y A063070 Adjacent sequences: A063067 A063068 A063069 this_sequence A063071 A063072 
               A063073
%K A063070 easy,sign
%O A063070 1,5
%A A063070 Jason Earls (zevi_35711(AT)yahoo.com), Aug 04 2001