A125618 - OEIS

%I #9 Feb 11 2024 17:26:38

%S 10,23,23,40,65,117,127,199,209,254,319,474,441,654,583,765,1071,826,

%T 1218,1252,1246,1476,1637,2000,2042,1899,2028,2974,3155,2998,3394,

%U 3593,4291,3983,4469,5525,4867,5743,5301,7274,5964,6321,7446,7684,9013,9099

%N (Sum of the squares of the quadratic nonresidues of prime(n)) / prime(n).

%C Always an integer for primes > 5.

%D D. M. Burton, Elementary Number Theory, McGraw-Hill, Sixth Edition (2007), p. 185.

%H Nick Hobson, <a href="/A125618/b125618.txt">Table of n, a(n) for n = 4..1000</a>

%F a(n) = A125617(n)/prime(n).

%e The quadratic nonresidues of 7=prime(4) are 3, 5 and 6. Hence a(4) = (3^2 + 5^2 + 6^2)/7 = 10.

%o (PARI) vector(46, m, p=prime(m+3); t=1; for(i=2, (p-1)/2, t+=((i^2)%p)^2); (p-1)*(2*p-1)/6-t/p)

%Y Cf. A076409, A076410, A125613-A125618.

%K easy,nonn

%O 4,1

%A _Nick Hobson_, Nov 30 2006