A372301 Erasing the digits that are not at the extremities of a(n) does not change the general succession of the sequence's digits. The sequence starts with a(1) = 99.

99, 111, 121, 201, 210, 112, 120, 131, 211, 2010, 113, 122, 141, 220, 1010, 151, 311, 202, 114, 132, 230, 1020, 1030, 115, 123, 161, 240, 221, 124, 133, 212, 3010, 1040, 2020, 1050, 3020, 171, 511, 203, 116, 142, 410, 222, 181, 204, 143, 302, 152, 3030, 1060

Offset

1,1

Comments

This is the lexicographically earliest sequence of distinct terms > 98 with this property.

The sequence starts with a(1) = 99 because starting with a(1) = 1 would have filled the Data section with the first 99 natural numbers.

Links

Table of n, a(n) for n=1..50.

Example

If we put parentheses around the digits that will be erased, and proceed, we will get those successive stages:
99, 111,  121,  201,  210,  112,  120,  131,  211,  2010,  113,  122,  141,
99,1(1)1,1(2)1,2(0)1,2(1)0,1(1)2,1(2)0,1(3)1,2(1)1,2(01)0,1(1)3,1(2)2,1(4)1,
99,1   1,1   1,2   1,2   0,1   2,1   0,1   1,2   1,2    0,1   3,1   2,1   1,
99,1   1 1 , 1 2   1,2   0 1 , 2 1   0,1   1 2 , 1 2    0,1   3 1 , 2 1   1,
We now see that the original sequence regenerates in some way.

Crossrefs

Cf. A127204, A127274.

Sequence in context: A171904 A171903 A072433 * A133650 A045298 A304951

Adjacent sequences: A372298 A372299 A372300 * A372302 A372303 A372304

Keyword

base,nonn

Author

Eric Angelini and Jean-Marc Falcoz, Apr 25 2024

Status

approved