A336954 Lexicographically earliest sequence of distinct positive terms such that, in the concatenation of the decimal representations of the terms, for any digit d at position p, d appears at some position q such that abs(p-q) = d.

1, 10, 2, 3, 20, 30, 4, 5, 6, 7, 40, 50, 60, 70, 8, 9, 11, 12, 32, 83, 90, 22, 220, 21, 13, 33, 333, 23, 24, 25, 34, 43, 52, 42, 26, 27, 28, 36, 63, 71, 18, 61, 14, 29, 240, 31, 130, 91, 15, 35, 53, 54, 55, 44, 37, 430, 41, 17, 45, 38, 93, 51, 16, 48, 49, 46

Offset: 1

Author

Rémy Sigrist, Aug 08 2020

Keywords

• nonn
• base

Comments

This sequence combines features of A322467 and of A336880.

Some numbers, like 121, cannot appear in this sequence.

Examples

			For n = 1:
- we can choose a(1) = 1.
For n = 2:
- a(2) must start with a digit 1,
- we can choose a(2) = 10.
For n = 3:
- we can choose a(3) = 2.
For n = 4:
- we can choose a(4) = 3.
For n = 5:
- a(5) must start with a digit 2,
- we can choose a(5) = 20.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program for A336954

Crossrefs

Cf. A322467, A336880.

Programs

PARI

\\ See Links section.