A217618 a(n) = A217578(n)/n.

3, 2, 3, 2, 3, 4, 5, 3, 11, 2, 3, 2, 3, 2, 5, 3, 3, 16, 3, 2, 15, 2, 5, 2, 3, 8, 5, 3, 11, 2, 3, 2, 3, 2, 5, 8, 3, 6, 3, 2, 13, 2, 13, 2, 3, 10, 11, 5, 11, 4, 3, 4, 3, 9, 13, 4, 3, 7, 3, 4, 13, 4, 5, 7, 3, 4, 5, 3, 11, 4, 5, 4, 7, 3, 5, 3, 7, 6, 5, 3, 17, 3

Offset

1,1

Comments

Inspired by Problem 300 in Mathematical Excalibur, Vol. 13, No. 1, February-April, 2008.

Links

Michel Marcus, Table of n, a(n) for n = 1..1000

Kin Y. Li, Problem 300, Mathematical Excalibur, Vol. 13, No. 1, February-April, 2008.

Example

For n=5, odd, 5*2=10, 5*3=15, so 3 is the smallest k such that all digits of 5*k are odd.
For n=8, even, 8*2=16, 8*3=24, so 3 is the smallest k such that all digits of 8*k are even.

Mathematica

Table[k = 2; While[d = IntegerDigits[k*n]; If[OddQ[n], done = And @@ OddQ[d], done = And @@ EvenQ[d]]; ! done, k++]; k, {n, 100}] (* T. D. Noe, Oct 10 2012 *)

Crossrefs

Cf. A217578.

Sequence in context: A379880 A029211 A246925 * A018837 A097618 A368276

Adjacent sequences: A217615 A217616 A217617 * A217619 A217620 A217621

Keyword

nonn,base

Author

Michel Marcus, Oct 09 2012

Status

approved