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A193413
Valley numbers.
4
1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 202, 212, 222, 303, 313, 323, 333, 404, 414, 424, 434, 444, 505, 515, 525, 535, 545, 555, 606, 616, 626, 636, 646, 656, 666, 707, 717, 727, 737, 747, 757, 767, 777, 808, 818, 828, 838, 848, 858, 868, 878, 888, 909, 919, 929, 939, 949, 959, 969, 979, 989, 999, 1001
OFFSET
1,2
COMMENTS
For n > 10 the structure of digits represents a valley. The first digit is equal to the last digit (1 - 9). The first digits are in nonincreasing order. The last digits are in nondecreasing order. The numbers may have more than one smallest digit. Sequence is infinite.
Superset of crater numbers (A193409) and A193412.
See valley numbers in base 2 (A193414 and A193415).
EXAMPLE
Illustration using 6543333346:
6 . . . . . . . . 6
. 5 . . . . . . . .
. . 4 . . . . . 4 .
. . . 3 3 3 3 3 . .
CROSSREFS
Cf. A134970. - Omar E. Pol, Aug 05 2011
Sequence in context: A276354 A084982 A110785 * A087992 A062687 A109882
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Jul 25 2011
EXTENSIONS
More terms extended by definition by Jaroslav Krizek, Jul 27 2011
STATUS
approved