A338935 a(n) = Sum_{d|n} (d^2 mod n).

0, 1, 1, 1, 1, 8, 1, 5, 1, 10, 1, 18, 1, 12, 20, 5, 1, 23, 1, 26, 17, 16, 1, 58, 1, 18, 10, 42, 1, 70, 1, 21, 32, 22, 40, 39, 1, 24, 23, 90, 1, 106, 1, 54, 71, 28, 1, 98, 1, 55, 44, 34, 1, 104, 37, 106, 29, 34, 1, 240, 1, 36, 77, 21, 65, 160, 1, 38, 56, 200, 1, 175, 1, 42, 60, 78, 94, 154, 1, 146

Offset: 1

Author

J. M. Bergot and Robert Israel, Nov 16 2020

Keywords

• nonn

Examples

			a(6) = (1^2 mod 6) + (2^2 mod 6) + (3^2 mod 6) + (6^2 mod 6) = 1+4+3+0 = 8.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000430 (a(n)=1), A338930 (a(n) is prime).

Programs

Maple

f:= n -> add(t^2 mod n, t = numtheory:-divisors(n)):
map(f, [$1..100]);

Mathematica

Table[Total[Mod[Divisors[n]^2,n]],{n,80}] (* Harvey P. Dale, Oct 11 2021 *)

PARI

a(n) = sumdiv(n, d, lift(Mod(d, n)^2)); \\ Michel Marcus, Nov 16 2020