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A336036
The leftmost digit L of a(n) jumps over L+1 digits to the left and is duplicated there; the rightmost digit R of a(n) jumps over R digits to the right and is duplicated there. Lexicographically earliest sequence of distinct positive integers with this property and a(1) = 11.
3
11, 1, 111, 112, 12, 21, 2, 13, 201, 3, 14, 1301, 4, 15, 16, 401, 5, 17, 601, 512, 172, 51, 211, 113, 18, 1311, 114, 1801, 411, 115, 19, 101, 511, 116, 911, 117, 611, 118, 1711, 119, 1811, 1112, 19201, 212, 22, 23, 202, 31, 213, 102, 32, 24, 203, 241, 311, 412, 1221, 214, 204, 242, 24201, 215, 205, 25, 501
OFFSET
1,1
COMMENTS
No term ends in 0 as this would force the next integer to start with zero.
LINKS
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
Cf. A336034 (duplication of the rightmost digit of a(n) to the right), A336035 (duplication of the leftmost digit of a(n) to the left).
Sequence in context: A278952 A120449 A101623 * A280330 A279937 A340566
KEYWORD
base,nonn
AUTHOR
Eric Angelini and Carole Dubois, Jul 17 2020
STATUS
approved