A075002 a(n) = smallest k such that A007908(k) is divisible by n.

1, 2, 2, 2, 5, 2, 11, 6, 8, 10, 106, 2, 11, 22, 5, 6, 21, 8, 27, 20, 11, 106, 33, 6, 25, 30, 26, 24, 31, 20, 46, 6, 113, 64, 45, 36, 21, 64, 11, 20, 3, 24, 19, 128, 35, 68, 8, 6, 53, 50, 21, 120, 83, 26, 135, 128, 27, 82, 104, 20

Offset: 1

Author

Amarnath Murthy, Sep 01 2002

Keywords

• base
• nonn

Comments

Conjecture: For every n, a(n) is well-defined.

The maximum of the first 10000 terms is a(6314) = 1002902 and A007908(1002902) is a 5902910-digit number. - Rick L. Shepherd, Oct 11 2015

Examples

			a(4) = 2 since A007908(2)=12 is divisible by 4.
a(7) = 11 as 7 divides A007908(11)=1234567891011 and 7 does not divide any smaller concatenations.
		

Links

• Rick L. Shepherd, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007908.

Programs

PARI

a(n)=my(m=Mod(1,n),k=1); while(m, m=10^#Str(k++)*m+k); k \\ Charles R Greathouse IV, Oct 11 2015

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003

Edited by Max Alekseyev, Sep 30 2015