A381530 a(n) is the least k > 0 such that n / k contains a digit 1 in its decimal representation.

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

Offset

1,2

Links

Table of n, a(n) for n=1..100.

Example

n = 7:
7/1 = 7
7/2 = 3.5
7/3 = 2.33...
7/4 = 1.75 contains a digit 1, thus a(7) = 4.

Mathematica

a[n_] := Module[{k = 1}, While[FreeQ[RealDigits[n/k][[1]], 1], k++]; k]; Array[a, 100] (* Amiram Eldar, Feb 26 2025 *)

Crossrefs

Cf. A317173, A371706.

Sequence in context: A262907 A341721 A290323 * A260254 A337853 A282711

Adjacent sequences: A381527 A381528 A381529 * A381531 A381534 A381535

Keyword

nonn,base,new

Author

Ctibor O. Zizka, Feb 26 2025

Status

approved