A243534 Numbers n such that the list of all divisors of n contains only 1 distinct digit (in base 10).

1, 11, 1111111111111111111, 11111111111111111111111

Offset: 1

Author

Jaroslav Krizek, Jun 13 2014

Keywords

• nonn
• base

Comments

Union of 1 and A004022 (prime repunits).

The next term has 317 digits.

Numbers n such that A037278(n), A176558(n) and A243360(n) contain only 1 distinct digit.

Examples

			11 is in sequence because the list of the divisors of 11: (1, 11) contains only 1 distinct digit.
		

Crossrefs

Cf. A095048, A037278, A176558, A243360.

Sequences of numbers n such that the list of divisors of n contains k distinct digits for 1 <= k <= 10: k = 1: A243534; k = 2: A243535; k = 3: A243536; k = 4: A243537; k = 5: A243538; k = 6: A243539; k = 7: A243540; k = 8: A243541; k = 9: A243542; k = 10: A095050.

Cf. A243543.

Programs

Excel

[Row n = 1 …10000; Column A: A(n) = A095048(n); Column B: B(n) = IF(A(n)=1;A(n)); Arrangement of column B]

Formula

a(1) = 1; for n >= 2, a(n+1) = A004022 (prime repunits).