OFFSET
0,2
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 is only one fixed point: a(0) = 0.
LINKS
EXAMPLE
A053985 = 0, 1, -2, -1, 4, 5, 2, 3, -8, -7, -10, -9, -4, -3, -6, -5, ...
We keep: 0, 2, 1, 8, 7, 10, 9, 4, 3, 6, 5, ...
PROG
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Oct 18 2020
STATUS
approved