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A125618 (Sum of the squares of the quadratic nonresidues of prime(n)) / prime(n). 6
10, 23, 23, 40, 65, 117, 127, 199, 209, 254, 319, 474, 441, 654, 583, 765, 1071, 826, 1218, 1252, 1246, 1476, 1637, 2000, 2042, 1899, 2028, 2974, 3155, 2998, 3394, 3593, 4291, 3983, 4469, 5525, 4867, 5743, 5301, 7274, 5964, 6321, 7446, 7684, 9013, 9099 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

Always an integer for primes > 5.

REFERENCES

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

LINKS

N. Hobson, Table of n, a(n) for n = 4..1000

N. Hobson, Home page (listed in lieu of email address)

FORMULA

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

EXAMPLE

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

PROG

(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)

CROSSREFS

Cf. A076409, A076410, A125613-A125618.

Sequence in context: A333104 A214959 A054095 * A341261 A154033 A275238

Adjacent sequences:  A125615 A125616 A125617 * A125619 A125620 A125621

KEYWORD

easy,nonn

AUTHOR

Nick Hobson, Nov 30 2006

STATUS

approved

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Last modified December 7 20:40 EST 2021. Contains 349589 sequences. (Running on oeis4.)