OFFSET
1,1
COMMENTS
No term ends in 0 as this would force the next integer to start with zero.
LINKS
Carole Dubois, Table of n, a(n) for n = 1..5000
EXAMPLE
The sequence starts with 11, 1, 111, 112, 12, 21, 2, 13, 201, 3,...
We don't duplicate to the left the leftmost digit of a(1) = 11 as there is no room.
The rightmost digit of a(1) = 11 is 1; we duplicate this digit in position 4;
The leftmost digit of a(2) = 1 is 1; we duplicate this digit in position 1;
The rightmost digit of a(2) = 1 is 1; we duplicate this digit in position 5;
The leftmost digit of a(3) = 111 is 1; we duplicate this digit in position 2;
The rightmost digit of a(3) = 111 is 1; we duplicate this digit in position 8;
The leftmost digit of a(4) = 112 is 1; we duplicate this digit in position 5;
The rightmost digit of a(4) = 112 is 2; we duplicate this digit in position 12;
The leftmost digit of a(5) = 12 is 1; we duplicate this digit in position 8;
The rightmost digit of a(5) = 12 is 2; we duplicate this digit in position 14;
The leftmost digit of a(6) = 21 is 2; we duplicate this digit in position 9; etc.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Jul 17 2020
STATUS
approved