A322511 Nonnegative numbers whose digits can be formed by typing adjacent keys on a 123-456-789 keypad without repeating a digit and without changing direction.
1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 21, 23, 25, 32, 36, 41, 45, 47, 52, 54, 56, 58, 63, 65, 69, 74, 78, 85, 87, 89, 96, 98, 123, 147, 258, 321, 369, 456, 654, 741, 789, 852, 963, 987
Offset: 1
Examples
The keypad is: +---+---+---+ | 1 | 2 | 3 | +---+---+---+ | 4 | 5 | 6 | +---+---+---+ | 7 | 8 | 9 | +---+---+---+ 258 can be formed in a straight line, while 256 cannot, even though 256 is formed with adjacent digits. Therefore 258 is a part of this sequence while 256 is not.
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