A395077 Lexicographically earliest infinite sequence of distinct positive numbers such that, for n > 2, a(n) shares a factor with a(n-1) and R(a(n)) shares a factor with R(a(n-1)), where R(k) is the digital reversal of k.

1, 2, 4, 6, 3, 9, 12, 15, 18, 21, 24, 8, 20, 22, 11, 33, 27, 30, 36, 39, 13, 26, 28, 14, 140, 154, 44, 40, 25, 45, 42, 46, 23, 69, 48, 51, 54, 50, 5, 55, 66, 57, 60, 62, 31, 93, 63, 49, 84, 64, 32, 96, 72, 75, 78, 81, 87, 29, 203, 210, 65, 70, 7, 77, 88, 68, 34, 206

Offset

1,2

Comments

As the sequence is infinite no term, except a(1), can be a power of 10.

There are no fixed points in the first 200000 terms other than the first two terms, although more may exist.

Links

Scott R. Shannon, Table of n, a(n) for n = 1..10000

Scott R. Shannon, Image of the first 200000 terms. The thin green line is a(n) = n.

Example

a(9) = 18 as 18 is unused, shares a factor with a(8) = 15, and R(18) = 81 shares a factor with R(15) = 51.

Crossrefs

Cf. A395189 (base 2), A004086, A064413, A391057, A393176.

Sequence in context: A356851 A291577 A393113 * A354434 A362842 A338059

Adjacent sequences: A395074 A395075 A395076 * A395078 A395079 A395080

Keyword

nonn,base

Author

Scott R. Shannon, Apr 11 2026

Status

approved