A357118 Numbers such that the first digit is the number of digits and the second digit is the number of distinct digits.

322, 323, 4222, 4224, 4242, 4244, 4300, 4303, 4304, 4311, 4313, 4314, 4322, 4323, 4324, 4330, 4331, 4332, 4335, 4336, 4337, 4338, 4339, 4340, 4341, 4342, 4345, 4346, 4347, 4348, 4349, 4353, 4354, 4355, 4363, 4364, 4366, 4373, 4374, 4377, 4383, 4384, 4388, 4393, 4394, 4399

Offset

1,1

Comments

By definition, each term must be at least a two-digit number.

The sequence is finite. The last term is 989765432.

There are 11041830 terms. - Michael S. Branicky, Oct 20 2022

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Example

322 is a term because the first digit is the number of digits = 3, and the second digit counts the different digits {2,3} = 2.

Prog

(Python)
def ok(n):
    s = str(n)
    if len(s) < 2 or len(s) > 9: return False
    return len(s) == int(s[0]) and len(set(s)) == int(s[1])
print([k for k in range(4394) if ok(k)]) # Michael S. Branicky, Oct 17 2022

Crossrefs

Cf. A319678.

Sequence in context: A105952 A062205 A054034 * A004947 A004967 A251231

Adjacent sequences: A357115 A357116 A357117 * A357119 A357120 A357121

Keyword

nonn,base,fini

Author

Marc Morgenegg, Oct 17 2022

Status

approved