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A273864
The successive numbers of digits visible between two even terms are given by the sequence itself.
0
0, 2, 1, 3, 4, 5, 6, 7, 11, 8, 9, 101, 10, 13, 103, 12, 15, 17, 19, 14, 21, 23, 105, 16, 25, 27, 29, 31, 107, 18, 33, 35, 37, 39, 20, 41, 43, 45, 109, 22, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 1001, 24, 139, 141, 1003, 26, 143, 145, 147, 1005, 28, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, 173, 175, 177, 179, 181, 183, 185, 187, 189
OFFSET
1,2
COMMENTS
The sequence starts with a(1)=0. It is then extended with the smallest integer not yet present and not leading to a contradiction.
EXAMPLE
The first two even terms that appear in the sequence are 0 and 2; between 0 and 2 there are 0 digits and this 0 corresponds to the starting 0 of the sequence.
The next even term is 4 and between 2 and 4 there are 2 digits [which are 1 and 3] and this 2 corresponds to the next term of the sequence.
The next even term is 6 and between 4 and 6 there is 1 digit [which is 5] and this 1 corresponds to the next term of the sequence.
The next even term is 8 and between 6 and 8 there are 3 digits [which are 7, 1 and 1] and this 3 corresponds to the next term of the sequence.
The next even term is 10 and between 8 and 10 there are 4 digits [which are 9, 1, 0 and 1] and this 4 corresponds to the next term of the sequence.
Etc.
CROSSREFS
Sequence in context: A155963 A375326 A273863 * A058684 A226054 A109920
KEYWORD
nonn,base
AUTHOR
Eric Angelini, Jun 01 2016
STATUS
approved