OFFSET
0,3
COMMENTS
This sequence is a permutation of the nonnegative integers, with inverse A336962.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 0..8191
Rémy Sigrist, Colored scatterplot of the first 2^16 terms (where the color is function of A090996(n))
FORMULA
a(n) = n iff n = 0 or n belongs to A140690.
EXAMPLE
The first terms, in decimal and in binary, are:
n a(n) bin(n) bin(a(n))
-- ---- ------ ---------
0 0 0 0
1 1 1 1
2 2 10 10
3 3 11 11
4 6 100 110
5 5 101 101
6 4 110 100
7 7 111 111
8 14 1000 1110
9 13 1001 1101
10 10 1010 1010
11 9 1011 1001
12 12 1100 1100
13 11 1101 1011
14 8 1110 1000
15 15 1111 1111
PROG
(PARI) toruns(n) = { my (r=[]); while (n, my (v=valuation(n+n%2, 2)); n\=2^v; r=concat(v, r)); r }
fromruns(r) = { my (v=0); for (k=1, #r, v=(v+k%2)*2^r[k]-k%2); v }
a(n) = { my (r=toruns(n)); fromruns(vector(#r, k, r[1+k%#r])) }
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Aug 09 2020
STATUS
approved