A362955 a(n) is the x-coordinate of the n-th point in a square spiral mapped to a square grid rotated by Pi/4 using the distance-limited strip bijection described in A307110.

0, 1, 0, -1, -2, -1, 0, 1, 2, 2, 1, 1, 0, 0, -1, -2, -3, -2, -1, -1, 0, 0, 1, 2, 3, 4, 3, 2, 2, 1, 0, -1, -1, -2, -3, -3, -4, -4, -3, -2, -2, -1, 0, 1, 1, 2, 3, 3, 4, 5, 4, 3, 3, 2, 1, 0, 0, -1, -2, -2, -3, -4, -4, -5, -5, -5, -4, -3, -3, -2, -1, 0, 0, 1, 2, 2, 3, 4, 4, 5, 5, 6

Offset: 0

Author

Hugo Pfoertner, May 10 2023

Keywords

• sign
• changed

Links

• Hugo Pfoertner, Table of n, a(n) for n = 0..3000
• Hugo Pfoertner, Plot of mapped spiral, using Plot 2.

Crossrefs

A362956 gives the corresponding y-coordinates.

Cf. A174344, A274923, A307110, A307731, A367150, A367895, A367896.

Programs

PARI

\\ ax(n), ay(n) after Kevin Ryde's functions in A174344 and A274923,
\\ p(i,j) given in A307110
ax(n) = {my(m=sqrtint(n), k=ceil(m/2)); n -= 4*k^2; if(n<0, if(n<-m, k, -k-n), if(n