A343642 Y-coordinate of points following the 3D square spiral defined in A343640.

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

Offset

0,39

Comments

See A343640 for more information 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) A343642_vec=concat([[P[2]| P<-A343640_row(n)] | n<-[0..2]]) \\ From 0 up to n there are (2n+1)^3 points with 3 coordinates each.

Crossrefs

Cf. A343641, A343643 (list of x and z-coordinates).

Cf. A343632 (variant using the Euclidean norm), A342562 (another variant).

Cf. A010014 (number of points on a shell with given radius => row lengths).

Sequence in context: A111409 A125088 A226456 * A268038 A274923 A249071

Adjacent sequences: A343639 A343640 A343641 * A343643 A343644 A343645

Keyword

sign,look,tabf

Author

M. F. Hasler, Apr 28 2021

Status

approved