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%I #16 Feb 13 2019 18:03:35
%S 1,2,0,1,0,1,0,2,0,1,0,0,0,0,0,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,0,0,
%U 0,0,0,1,0,2,0,1,0,1,0,2,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N An example of a d-perfect sequence: a(n) = A006318(n-1) mod 3.
%H Antti Karttunen, <a href="/A039975/b039975.txt">Table of n, a(n) for n = 1..11000</a>
%H D. Kohel, S. Ling and C. Xing, <a href="http://www.maths.usyd.edu.au/u/kohel/doc/perfect.ps">Explicit Sequence Expansions</a>, in Sequences and their Applications, C. Ding, T. Helleseth, and H. Niederreiter, eds., Proceedings of SETA'98 (Singapore, 1998), 308-317, 1999. DOI: 10.1007/978-1-4471-0551-0_23
%F a(n) = A006318(n-1) mod 3. - _Christian G. Bower_, Jun 12 2005
%o (PARI)
%o A006318(n) = if( n<1, 1, sum( k=0, n, 2^k * binomial( n, k) * binomial( n, k-1)) / n);
%o A039975(n) = (A006318(n-1) % 3); \\ _Antti Karttunen_, Feb 13 2019
%Y Cf. A006318.
%Y Cf. also A039969.
%K nonn
%O 1,2
%A _N. J. A. Sloane_.
%E More terms from _Christian G. Bower_, Jun 12 2005
%E Bower's formula added to the name by _Antti Karttunen_, Feb 13 2019
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