A276684 Between two successive even digits "a" and "b" there are exactly |a-b| odd digits.

0, 1, 3, 2, 5, 7, 4, 9, 11, 10, 13, 15, 17, 6, 19, 8, 31, 33, 35, 21, 14, 37, 22, 23, 30, 39, 25, 34, 41, 12, 27, 50, 51, 29, 53, 16, 55, 43, 32, 57, 44, 45, 36, 59, 47, 52, 71, 49, 56, 61, 18, 73, 63, 38, 75, 65, 54, 77, 66, 67, 58, 79, 69, 74, 91, 93, 81, 76, 95, 83, 96, 97, 85, 99, 94, 111, 70, 112, 110, 113, 115, 118

Offset

1,3

Comments

The sequence is started with a(1) = 0 and always extended with the smallest unused integer not leading to a contradiction.

The sequence is not a permutation of the natural numbers as 42, for instance, will never appear (according to the definition, 42 should show |4-2| odd digits between " 4 " and " 2 " and shows none).

Links

Jean-Marc Falcoz, Table of n, a(n) for n = 1..10004

Example

Between the first 0 and the first 2 of the sequence, there are indeed |0-2| = 2 odd digits (1 and 3).
Between the first 2 and the first 4 of the sequence, there are indeed |2-4| = 2 odd digits (5 and 7).
Between the first 4 and the second 0 of the sequence, there are indeed |4-0| = 4 odd digits (9,1,1 and 1).
Between the second 0 and the first 6 of the sequence, there are indeed |0-6| = 6 odd digits (1,3,1,5,1 and 7).
Between the first 6 and the first 8 of the sequence, there are indeed |6-8| = 2 odd digits (1 and 9).

Crossrefs

Sequence in context: A364885 A006369 A097284 * A105353 A115966 A338744

Adjacent sequences: A276681 A276682 A276683 * A276685 A276686 A276687

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Sep 13 2016

Status

approved