OFFSET
0,3
COMMENTS
This sequence is a self-inverse permutation of the nonnegative integers (the offset has been set to 0 so as to get a permutation).
There are only two fixed points: a(0) = 0 and a(1) = 1.
LINKS
EXAMPLE
A053985 = 0, 1, -2, -1, 4, 5, 2, 3, -8, -7, -10, -9, -4, -3, -6, -5, 16, 17, ...
We keep: 0, 1, 4, 5, 2, 3, 16, 17, ...
PROG
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Oct 18 2020
STATUS
approved