A039972 An example of a d-perfect sequence: a(n) = A007317(n) mod 3.

1, 2, 2, 0, 0, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 1, 1, 0, 0, 1, 1, 2, 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, 2, 2, 1, 1, 0, 0, 1, 1, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 0, 0, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

Odd bisection seems to be A006996. See also A039969. - Antti Karttunen, Aug 15 2017

Links

• Antti Karttunen, Table of n, a(n) for n = 1..6561
• D. Kohel, S. Ling and C. Xing, Explicit Sequence Expansions, 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

Crossrefs

Cf. A006996, A007317, A010872, A039969.

Programs

PARI

write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
A039972_as_a_vector(size)= { my(A=vector(size)); for(j=1, size, A[j]=1+sum(k=1, j-1, A[k]*A[j-k])); apply(n->(n%3),A); }; \\ After Michael Somos' May 23 2005 code for A007317 and Christian G. Bower's formula for A039972.
write_to_bfile(1,A039972_as_a_vector(6561),"b039972_upto6561.txt"); \\ Antti Karttunen, Aug 15 2017

Formula

a(n) = A007317(n) mod 3. - Christian G. Bower, Jun 12 2005

Extensions

More terms from Christian G. Bower, Jun 12 2005

Formula added to the name by Antti Karttunen, Aug 15 2017