A095250 a(n) = 11111111... (n times) = (10^n-1)/9 reduced mod n.

0, 1, 0, 3, 1, 3, 1, 7, 0, 1, 1, 3, 1, 11, 6, 7, 1, 9, 1, 11, 6, 11, 1, 15, 11, 11, 0, 19, 1, 21, 1, 7, 12, 11, 16, 27, 1, 11, 33, 31, 1, 21, 1, 11, 36, 11, 1, 39, 36, 11, 9, 19, 1, 27, 1, 39, 54, 11, 1, 51, 1, 11, 27, 7, 61, 33, 1, 23, 42, 61, 1, 63, 1, 11, 36, 47, 23, 39, 1, 71, 0, 11, 1, 63

Offset: 1

Author

Amarnath Murthy, Jun 17 2004

Keywords

• nonn

Comments

a(p) = 1 if p is a prime; a(3^k) = 0.

Examples

			1111111 mod 7 = 1.
		

References

• Amarnath Murthy, "On the divisors of Smarandache Unary Sequence", Smarandache Notions Journal, 1-2-3, vol. 11, 2000.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A002275.

Programs

Mathematica

Table[Mod[FromDigits[PadRight[{},n,1]],n],{n,90}] (* Harvey P. Dale, Jun 19 2022 *)

PARI

a(n) = (10^n - 1)/9 % n; \\ Michel Marcus, Jul 03 2019

Formula

a(n) = A002275(n) mod n.