OFFSET
0,9
COMMENTS
Derived from G.J. Chaitin's s formula.
Chaitin's expression is s(0)=0, s(1)=alpha, s(2)=1, s(n)=Sum{ s[n-k]*s[k], k=2..n-1}, but here it is made to alternate with the introduction of (-1)^k so that the numbers do not get large fast and alternate back and forth like a boustrophedon (A072231).
REFERENCES
G.J. Chaitin, Algorithmic Information Theory, Cambridge Press, 1987, page 169.
MATHEMATICA
s[n_Integer?Positive] := s[n]=Abs[Sum[(-1)^k*s[k-n]*s[k], {k, 2, n-1}]; s[0]=0; s[1]=1; s[2]=1; Table[ s[n], {n, 0, 200, 2}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jul 25 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Jul 29 2002
STATUS
approved