OFFSET
0,6
COMMENTS
The odd function f such that f(n) = (a(n), A340172(n)) for any n >= 0 will visit exactly once every lattice point (so it is a bijection from Z to Z^2).
LINKS
Rémy Sigrist, Table of n, a(n) for n = 0..10000
Rémy Sigrist, PARI program for A340171
FORMULA
a(n) = 0 iff n belongs to A014105.
EXAMPLE
The spiral starts as follows:
+-----+-----+-----+-----+-----+
. |
. |
. +-----+-----+-----+ +
. |5 4 3 |2 |
. | | |
+ +-----+-----+ +
|6 | 0 1 | .
| | | .
+ +-----+-----+-----+ .
|7 .
| .
+-----+-----+-----+-----+-----+
8 9 10 11 12 13
- so a(0) = a(3) = a(10) = 0,
- a(1) = a(2) = a(11) = 1.
PROG
(PARI) See Links section.
CROSSREFS
KEYWORD
sign
AUTHOR
Rémy Sigrist, Dec 30 2020
STATUS
approved