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A343641
X-coordinate of points following the 3D square spiral defined in A343640.
6
0, 0, 1, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 0, 0, 1, 1, 0, -1, -1, -1, 0, 1, 2, 2, 2, 1, 0, -1, -2, -2, -2, -2, -2, -1, 0, 1, 2, 2, 2, 2, 2, 1, 0, -1, -2, -2, -2, -2, -2, -1, 0, 1, 2, 2, 2, 2, 2, 1, 0, -1, -2, -2, -2, -2, -2, -1, 0, 1, 2, 2, 2, 2, 2, 1, 0, -1, -2, -2, -2, -2, -2, -1, 0
OFFSET
0,37
COMMENTS
See A343640 for more about this 3D generalization of the 2D Ulam type square spiral.
The sequence can be seen as a table with row lengths A010014, where A010014(r) is the number of points of Z^3 with sup-norm r.
LINKS
PROG
(PARI) A343641_vec=concat([[P[1]| P<-A343640_row(r)] | r<-[0..2]]) \\ From r=0 up to n there are (2n+1)^3 points with 3 coordinates each.
CROSSREFS
Cf. A343640 (triples), A343642 and A343643 (list of y and z-coordinates).
Cf. A343631 (variant using the Euclidean norm), A342561 (another variant).
Cf. A010014 (number of points on a shell with given radius => row lengths).
Sequence in context: A307013 A345978 A307012 * A112211 A246575 A357563
KEYWORD
sign,tabf
AUTHOR
M. F. Hasler, Apr 28 2021
STATUS
approved