A071957 - OEIS

%I #10 Jan 04 2013 18:31:40

%S 1,1,0,2,0,2,0,0,6,2,0,0,0,4,0,8,0,0,0,0,0,2,0,0,20,6,0,0,0,4,0,0,0,4,

%T 0,12,0,6,0,0,0,4,0,0,0,4,0,0,42,2,0,0,0,2,0,0,0,2,0,0,0,8,0,32,0,8,0,

%U 0,0,4,0,0,0,10,0,0,0,4,0,0,54,4,0,0,0,10,0,0,0,4,0,0,0,8,0,0,0,2,0,40

%N Sum( i=1, n, K(i,n) ) where K(x,y) is the Kronecker symbol (x/y).

%C a(n) is always >= 0

%t Table[Sum[KroneckerSymbol[i, n], {i, n}], {n, 100}] (* _Alonso del Arte_, Dec 26 2012 *)

%o (PARI) for(n=1,100,print1(sum(i=1,n,kronecker(i,n)),","))

%K easy,nonn

%O 1,4

%A _Benoit Cloitre_, Jun 16 2002