

A276684


Between two successive even digits "a" and "b" there are exactly ab odd digits.


1



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
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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 42 odd digits between " 4 " and " 2 " and shows none).


LINKS

JeanMarc 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 02 = 2 odd digits (1 and 3).
Between the first 2 and the first 4 of the sequence, there are indeed 24 = 2 odd digits (5 and 7).
Between the first 4 and the second 0 of the sequence, there are indeed 40 = 4 odd digits (9,1,1 and 1).
Between the second 0 and the first 6 of the sequence, there are indeed 06 = 6 odd digits (1,3,1,5,1 and 7).
Between the first 6 and the first 8 of the sequence, there are indeed 68 = 2 odd digits (1 and 9).


CROSSREFS

Sequence in context: A265903 A006369 A097284 * A105353 A115966 A203602
Adjacent sequences: A276681 A276682 A276683 * A276685 A276686 A276687


KEYWORD

nonn,base


AUTHOR

Eric Angelini and JeanMarc Falcoz, Sep 13 2016


STATUS

approved



