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 A255643 Difference between sums of quadratic residues and non-residues modulo n that are coprime to n. 3

%I

%S 0,1,-1,-2,0,-4,-7,-14,-3,0,-11,-22,0,0,-50,-44,0,-12,-19,-60,-84,-44,

%T -69,-94,0,0,-9,-98,0,-80,-93,-152,-176,0,-280,-138,0,-76,-312,-300,0,

%U -126,-43,-286,-330,0,-235,-332,-49,0,-476,-364,0,-36,-660,-602,-570,0,-177,-380,0,0,-630,-560,-780,-374,-67,-680,-782,-560,-497,-714,0,0,-850,-798,-1232,-468,-395,-1080,-27,0,-249,-882,-1360,-172,-1508,-1430,0,-600,-1820,-1058,-1674,0,-2090,-1240,0,0,-1518,-1100

%N Difference between sums of quadratic residues and non-residues modulo n that are coprime to n.

%F For prime n, a(n) = A228131(n) = A255644(n).

%F For prime n==1 (mod 4), a(n) = 0.

%F For prime n==3 (mod 4) and n>3, i.e., n=A002145(m) for m>1, a(n) = -n*A002143(m).

%o (PARI) { A255643(n) = my(r); r=0; for(i=0,n-1, if(gcd(i,n)>1,next); if(issquare(Mod(i,n)), r+=i, r-=i) ); r }

%Y C.f. A228131, A255644

%K sign

%O 1,4

%A _Max Alekseyev_, Mar 01 2015

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Last modified October 15 09:22 EDT 2019. Contains 328026 sequences. (Running on oeis4.)