%I A007012 M0248
%S A007012 1,0,2,2,3,2,5,2,5,4,5,2,8,2,9,8,9,2,9,2,11,8,9,2,15,6,9,10,15,2,20,2,
               17,
%T A007012 8,5,10,15,2,9,10,19,2,23,2,19,20,17,2,29,8,17,20,19,2,29,10,24,8,17,2,
%U A007012 35,2,33,18,33,16,19,2,11,20,27,2,33,2,9,30,19,16,41,2,31,28,9,2,32,16
%N A007012 a(n) is number of k for which C(n,k) is not divisible by n.
%C A007012 The number of nonzero terms in the polynomial (1+x)^n (mod n). Note that 
               n is prime iff a(n)=2. - T. D. Noe (noe(AT)sspectra.com), Feb 23 
               2006
%D A007012 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A007012 J. H. Conway, personal communication.
%H A007012 T. D. Noe, <a href="b007012.txt">Table of n, a(n) for n = 0..1000</a>
%F A007012 a(n)=n+1-A020475(n) - T. D. Noe (noe(AT)sspectra.com), Feb 23 2006
%t A007012 Prepend[ Array[ Length[ Select[ Table[ Binomial[ #, k ]/#, {k, 0, #} 
               ], !IntegerQ[ # ]& ] ]&, 100 ], 1 ]
%Y A007012 Sequence in context: A100565 A010846 A073023 this_sequence A062830 A164941 
               A115119
%Y A007012 Adjacent sequences: A007009 A007010 A007011 this_sequence A007013 A007014 
               A007015
%K A007012 nonn
%O A007012 0,3
%A A007012 N. J. A. Sloane (njas(AT)research.att.com).