A328818 2 * x-coordinate of the points of a counterclockwise spiral on an hexagonal grid.

0, 2, 1, -1, -2, -1, 1, 3, 4, 3, 2, 0, -2, -3, -4, -3, -2, 0, 2, 4, 5, 6, 5, 4, 3, 1, -1, -3, -4, -5, -6, -5, -4, -3, -1, 1, 3, 5, 6, 7, 8, 7, 6, 5, 4, 2, 0, -2, -4, -5, -6, -7, -8, -7, -6, -5, -4, -2, 0, 2, 4, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 3, 1, -1, -3, -5, -6, -7, -8, -9, -10, -9, -8, -7, -6, -5, -3, -1

Offset: 0

Author

Hugo Pfoertner, Oct 28 2019

Keywords

• sign

Comments

The Cartesian coordinates of the points of a counterclockwise spiral on an hexagonal grid are given by x(n) = a(n)/2 and by y(n)= A307012(n) * sqrt(3)/2.

Links

• Hugo Pfoertner, Table of n, a(n) for n = 0..10000
• Hugo Pfoertner, Illustration of spiral.
• Index entries for sequences related to coordinates of 2D curves

Crossrefs

Cf. A307011, A307012, A307013.

Formula

a(n) = A307011(n) + A307013(n).