%I M0004
%S 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N Twice A000007.
%C Multiplicative with a(p^e) = 0.  _Mitch Harris_, Jun 09 2005
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H James Spahlinger, <a href="/A000038/b000038.txt">Table of n, a(n) for n = 0..10000</a>
%H Daniele A. Gewurz and Francesca Merola, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL6/Gewurz/gewurz5.html">Sequences realized as Parker vectors of oligomorphic permutation groups</a>, J. Integer Seqs., Vol. 6, 2003.
%F a(n) = 2*A000007(n) = (1)^A000040(n) + 1.  _JuriStepan Gerasimov_, Oct 29 2009
%o (Haskell)
%o a000038 n = 2 * a000007 n  _James Spahlinger_, Oct 08 2012
%o (PARI) a(n)=if(n,0,2) \\ _Charles R Greathouse IV_, Oct 09 2012
%Y Cf. A007395, A000007.
%K easy,nonn,mult
%O 0,1
%A _N. J. A. Sloane_
