OFFSET
1,2
COMMENTS
Leading zeros are ignored.
This sequence is a permutation of the positive integers with inverse A360472:
- if a(n) < 10^e, then we can extend the sequence with a number of the form a(n) + k * 10^e (with k > 0),
- by the pigeonhole principle, there are infinitely many terms starting with the same nonzero digit, say with d,
- every number of the form 10*k + d (with k >= 0) appears in the sequence,
- any number v can appear after a term of the form v * 10^k + d (with k > 0).
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..10000
Rémy Sigrist, Scatterplot of the first 1000000 terms
Rémy Sigrist, PARI program
EXAMPLE
The first terms are:
n a(n) a(n) aligned
-- ---- ------------
1 1 1
2 11 11
3 21 21
4 2 2
5 12 12
6 31 31
7 3 3
8 13 13
9 41 41
10 4 4
11 14 14
12 51 51
PROG
(PARI) See Links section.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Feb 08 2023
STATUS
approved