A193413 - OEIS

A193413

Valley numbers.

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

(list; graph; refs; listen; history; text; internal format)

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).

LINKS

Table of n, a(n) for n=1..73.

EXAMPLE

Illustration using 6543333346:

6 . . . . . . . . 6

. 5 . . . . . . . .

. . 4 . . . . . 4 .

. . . 3 3 3 3 3 . .

CROSSREFS

Cf. A110785, A193409, A193412, A193414, A193415.