A317173 a(n) is the least k > 0 such that k * n contains a digit 1 in its decimal representation.

1, 5, 4, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 5, 5, 5, 4, 4, 3, 4, 4, 4, 1, 4, 4, 3, 3, 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 3, 3, 3, 3, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2

Offset: 1

Author

Rémy Sigrist, Jul 23 2018

Keywords

• nonn
• base
• easy

Examples

			The multiples of 3 are: 3, 6, 9, 12, 15, etc.; 12 is the first one containing the digit 1, hence a(3) = 12/3 = 4.
		

Crossrefs

Cf. A011531, A190302, A317175.

Programs

PARI

a(n) = for (k=1, oo, if (setsearch(Set(digits(k*n)), 1), return (k)))

Formula

1 <= a(n) <= 5.

a(n) <= A190302(n).

a(n) = A317175(n, 1).

a(10 * n) = a(n).