A343641 X-coordinate of points following the 3D square spiral defined in A343640.

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

Hugo Pfoertner, Table of n, a(n) for n = 0..9260

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

Adjacent sequences: A343638 A343639 A343640 * A343642 A343643 A343644

Keyword

sign,tabf

Author

M. F. Hasler, Apr 28 2021

Status

approved