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A277519
Each odd digit "k" is followed by k even digits.
2
1, 2, 3, 4, 6, 8, 5, 20, 22, 21, 23, 24, 25, 26, 28, 27, 40, 42, 44, 29, 46, 48, 60, 62, 41, 43, 64, 45, 66, 68, 47, 80, 82, 84, 49, 86, 88, 200, 201, 61, 63, 202, 7, 204, 206, 65, 208, 203, 220, 9, 222, 224, 226, 10, 12, 14, 16, 18, 30, 205, 228, 207, 240, 242, 67, 244, 246, 69, 248, 260, 262, 32, 209, 264, 266, 268
OFFSET
1,2
COMMENTS
The sequence starts with a(1) = 1 and was always extended with the smallest integer not yet present that does not lead to a contradiction.
LINKS
EXAMPLE
As a(1) = 1, we must have for a(2) an integer starting with an even digit; thus a(2) = 2, this integer being the smallest available one that does not lead to a contradiction; we extend then the sequence with a(3) = 3; this value "3" means that the next 3 digits must be even; we thus extend the sequence with a(4) = 4, a(5) = 6 and a(6) = 8; the next integer must start with an odd digit, thus a(7) = 5, which is the smallest available integer that doesn't lead to a contradiction; this value "5" means that the next 5 digits must be even; we thus extend the sequence with a(8) = 20, a(9) = 22 and a(10) = 21; etc.
CROSSREFS
Cf. A277518.
Sequence in context: A257725 A257690 A336322 * A277623 A082315 A342266
KEYWORD
nonn,base
AUTHOR
STATUS
approved