login
A263443
A self-describing sequence: when the sequence is read as a string of decimal digits, a(n) gives the starting position of an occurrence of n. This sequence is the lexicographically earliest one with this property.
2
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 1, 17, 130, 21, 50, 15, 28, 180, 33, 20, 37, 2, 200, 42, 52, 47, 270, 162, 60, 57, 310, 300, 3, 66, 350, 35, 73, 380, 78, 400, 41, 84, 302, 4, 91, 460, 96, 480, 22, 104, 510, 110, 530, 115, 5, 55, 122, 580, 53, 132, 146, 136
OFFSET
1,2
COMMENTS
The sequence does not necessarily give the earliest position of a number.
For example, 1234 first appears at position 1, but a(1234) = 28011.
EXAMPLE
The following table lists few first terms, with the corresponding digits induced in the overall sequence:
+----+------+------------------------------------------------------------+
| n | a(n) | New known digits |
+----+------+------------------------------------------------------------+
| 1 | 1 | 1 |
| 2 | 2 | 2 |
| 3 | 3 | 3 |
| 4 | 4 | 4 |
| 5 | 5 | 5 |
| 6 | 6 | 6 |
| 7 | 7 | 7 |
| 8 | 8 | 8 |
| 9 | 9 | 9 |
| 10 | 10 | 10 |
| 11 | 14 | 1411 |
| 12 | 1 | |
| 13 | 17 | 713 |
| 14 | 130 | 0 ... 14 |
| 15 | 21 | 215 |
| 16 | 50 | 0 16 |
| 17 | 15 | 15 |
| 18 | 28 | 2818 |
+----+------+------------------------------------------------------------+
PROG
(Perl) See Links section.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paul Tek, Oct 18 2015
STATUS
approved