A324480 Consider the numbers on the x-axis in the spiral shown in A274641; a(n) is the distance from n to the origin, or -1 if n never appears on the x-axis.

0, 1, 1, 2, 2, 3, 4, 3, 7, 6, 4, 5, 8, 10, 5, 6, 7, 11, 8, 12, 14, 10, 18, 9, 9, 13, 12, 20, 21, 24, 11, 22, 13, 14, 16, 17, 15, 15, 17, 18, 19, 36, 16, 23, 26, 23, 21, 27, 19, 27, 28, 20, 22, 25, 24, 43, 29, 47, 50, 25, 26, 37, 43, 49, 34, 28, 42, 52, 53, 30, 30

Offset: 0

Author

N. J. A. Sloane, Mar 11 2019

Keywords

• nonn

Comments

It is conjectured that every nonnegative number appears on the x-axis exactly once.

a(n) is also the distance to the origin from the point n+1 on the x-axis in A274640.

Examples

			The portion of the x-axis near 0 is:
... 14   6   5   4   2   0   1   3   7  10  11 ...
and we see that both 1 and 2 are at distance 1 from 0. So a(1) = a(2) = 1.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..4999
• Rémy Sigrist, PARI program for A324480

Crossrefs

Cf. A274640, A274641.

The positive and negative x-axes are given in A274924 and A274928.

Programs

PARI

See Links section.

Extensions

More terms from Jinyuan Wang, Feb 27 2020