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A137667
The sequence alternates even and odd integers but also even and odd digits; it is monotonically increasing and a(n) is always the smallest integer fitting the pattern.
0
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 210, 301, 410, 501, 610, 701, 810, 901, 21010, 30101, 41010, 50101, 61010, 70101, 81010, 90101, 2101010, 3010101, 4101010, 5010101, 6101010, 7010101, 8101010, 9010101, 210101010, 301010101, 410101010, 501010101
OFFSET
0,3
EXAMPLE
The integer after "9" must be even, must start with an even digit and must be the smallest one larger than "9"; only "210" satisfies all requirements. The integer after "210" must be odd, must start with an odd digit and must be the smallest one larger than "210"; only "301" fits, etc.
CROSSREFS
Sequence in context: A061276 A249515 A217555 * A117954 A342952 A029966
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini, Apr 27 2008
STATUS
approved