

A047896


For given n, consider all 4tuples P = (a,b,c,d) with P.P = n; let d = squared distance to the line OP from the closest point of Z^n (excluding the endpoints); sequence gives max_P d*n.


7



1, 1, 2, 3, 1, 2, 3, 0, 2, 4, 2, 3, 3, 3, 5, 0, 2, 5, 3, 4, 5, 6, 5, 0, 6, 4, 5, 3, 5, 9, 6, 0, 6, 8, 6, 8, 9, 8, 9, 0, 5, 6, 5, 8, 9, 11, 10, 0, 6, 11, 9, 4, 10, 11, 10, 0, 14, 9, 11, 11, 9, 11, 14, 0, 14, 11, 11, 8, 11, 19, 14, 0, 9, 11, 11, 8, 10, 14, 14, 0, 14, 10, 13, 20, 21
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OFFSET

1,3


COMMENTS

A form of generalized GCD of 4 numbers.


LINKS

Table of n, a(n) for n=1..85.
N. J. A. Sloane, Vinay A. Vaishampayan and Sueli I. R. Costa, Fat Struts: Constructions and a Bound, Proceedings Information Theory Workshop, Taormino, Italy, 2009. [Cached copy]
N. J. A. Sloane, Vinay A. Vaishampayan and Sueli I. R. Costa, A Note on Projecting the Cubic Lattice, Discrete and Computational Geometry, Vol. 46 (No. 3, 2011), 472478.
N. J. A. Sloane, Vinay A. Vaishampayan and Sueli I. R. Costa, The Lifting Construction: A General Solution to the Fat Strut Problem, Proceedings International Symposium on Information Theory (ISIT), 2010, IEEE Press. [Cached copy]


EXAMPLE

n=10, best P is (1,1,2,2), closest point of Z^4 to OP is (0,0,1,1) at squared distance d = 2/5, so a(10) = 10*2/5 = 4.


CROSSREFS

Cf. A059804, A059774.
Sequence in context: A205003 A159956 A053839 * A073645 A294180 A179542
Adjacent sequences: A047893 A047894 A047895 * A047897 A047898 A047899


KEYWORD

nonn


AUTHOR

N. J. A. Sloane and Vinay Vaishampayan, Feb 27 2001


STATUS

approved



