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A095250 a(n) = 11111111... (n times) = (10^n-1)/9 reduced mod n. 4

%I #10 Jun 19 2022 11:16:06

%S 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,

%T 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,

%U 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

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

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

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

%H Harvey P. Dale, <a href="/A095250/b095250.txt">Table of n, a(n) for n = 1..1000</a>

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

%e 1111111 mod 7 = 1.

%t Table[Mod[FromDigits[PadRight[{},n,1]],n],{n,90}] (* _Harvey P. Dale_, Jun 19 2022 *)

%o (PARI) a(n) = (10^n - 1)/9 % n; \\ _Michel Marcus_, Jul 03 2019

%Y Cf. A002275.

%K nonn

%O 1,4

%A _Amarnath Murthy_, Jun 17 2004

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Last modified April 24 00:30 EDT 2024. Contains 371917 sequences. (Running on oeis4.)