cp's OEIS Frontend

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

%I A338935 #13 Oct 11 2021 16:53:44
%S A338935 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,
%T A338935 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,
%U A338935 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
%N A338935 a(n) = Sum_{d|n} (d^2 mod n).
%H A338935 Robert Israel, <a href="/A338935/b338935.txt">Table of n, a(n) for n = 1..10000</a>
%e A338935 a(6) = (1^2 mod 6) + (2^2 mod 6) + (3^2 mod 6) + (6^2 mod 6) = 1+4+3+0 = 8.
%p A338935 f:= n -> add(t^2 mod n, t = numtheory:-divisors(n)):
%p A338935 map(f, [$1..100]);
%t A338935 Table[Total[Mod[Divisors[n]^2,n]],{n,80}] (* _Harvey P. Dale_, Oct 11 2021 *)
%o A338935 (PARI) a(n) = sumdiv(n, d, lift(Mod(d, n)^2)); \\ _Michel Marcus_, Nov 16 2020
%Y A338935 Cf. A000430 (a(n)=1), A338930 (a(n) is prime).
%K A338935 nonn
%O A338935 1,6
%A A338935 _J. M. Bergot_ and _Robert Israel_, Nov 16 2020