A231167 a(1) = a(2) = 0, for n>=3: (sum of non-divisors of n) modulo (number of non-divisors of n).

0, 0, 0, 0, 0, 1, 0, 1, 2, 1, 0, 2, 0, 1, 8, 6, 0, 0, 0, 0, 12, 1, 0, 0, 8, 1, 16, 20, 0, 19, 0, 23, 20, 1, 24, 8, 0, 1, 24, 26, 0, 25, 0, 32, 21, 1, 0, 26, 18, 38, 32, 38, 0, 31, 40, 36, 36, 1, 0, 30, 0, 1, 31, 15, 48, 37, 0, 50, 44, 47, 0, 33, 0, 1, 35, 56

Offset: 1

Author

Jaroslav Krizek, Nov 07 2013

Keywords

• nonn

Comments

a(n) = 0 for n = 1, 2 and numbers from A140826.

a(n) = 1 for numbers of form 2*p (p=prime) from A100484 and other numbers, e.g. 8 and 13456 are only numbers n < 10^5 which are not of form 2*p with a(n) = 1.

Examples

			For n=6, a(6) = A024816(6) mod A049820(6) = 9 mod 2 = 1.
		

Links

• Jaroslav Krizek, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A054025 (sigma(n) mod tau(n)), A024816, A049820, A024816, A049820, A065091, A230605, A161344.

Programs

Mathematica

ndn[n_]:=Module[{nd=Complement[Range[n],Divisors[n]]},Mod[Total[ nd],Length[ nd]]]; Join[{0,0},Array[ndn,80,3]] (* Harvey P. Dale, Apr 11 2022 *)

Formula

a(n) = A024816(n) mod A049820(n).