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

1,2

Comments

Subsequence of A280593.

Diagonal moves are not allowed.

Links

Table of n, a(n) for n=1..45.

Example

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.

Crossrefs

Cf. A280593, A280594, A280595, A281942.

Sequence in context: A281942 A280594 A280593 * A171827 A322002 A107743

Adjacent sequences: A322508 A322509 A322510 * A322512 A322513 A322514

Keyword

nonn,full,fini,base

Author

Jason Jewell, Dec 13 2018

Status

approved