A339138 Lexicographically earliest sequence of distinct nonnegative terms such that the first digit d of a(n), for n > 1, is the sum of the two closest digits of d (they are the rightmost digit of a(n-1) and the next digit on the right of d).

0, 1, 10, 11, 21, 32, 20, 22, 31, 43, 30, 33, 41, 54, 40, 44, 51, 65, 50, 55, 61, 76, 60, 66, 71, 87, 70, 77, 81, 98, 80, 88, 91, 100, 99, 90, 110, 111, 101, 102, 42, 53, 52, 64, 62, 75, 72, 86, 82, 97, 92, 200, 112, 201, 103, 63, 74, 73, 85, 83, 96, 93, 300, 113, 301, 104, 95, 94, 84, 400, 114, 401, 105, 500, 115

Offset

1,3

Comments

The first two digits of a(n) cannot be in ascending order.

Links

Table of n, a(n) for n=1..75.

Maple

a(2) = 1 and 1 is the sum of 0 + 1 (closest digits to 1);
a(3) = 10 and 1 is the sum of 1 + 0 (closest digits to 1);
a(4) = 11 and the first 1 is the sum of 0 + 1 (closest digits to 1);
a(5) = 21 and 2 is the sum of 1 + 1 (closest digits to 2); etc.

Crossrefs

Cf. A339139 (where the last digit is involved, instead of the first digit).

Sequence in context: A255536 A298849 A277588 * A022100 A041475 A041204

Adjacent sequences: A339135 A339136 A339137 * A339139 A339140 A339141

Keyword

base,nonn

Author

Eric Angelini, Nov 25 2020

Status

approved