A071782 Sum of distinct squares in Z_n (mod n).

0, 1, 1, 1, 0, 2, 0, 5, 3, 5, 0, 2, 0, 0, 0, 14, 0, 6, 0, 15, 7, 0, 0, 18, 0, 13, 18, 0, 0, 0, 0, 8, 0, 17, 0, 24, 0, 0, 13, 15, 0, 14, 0, 22, 0, 0, 0, 28, 0, 25, 0, 39, 0, 9, 0, 28, 19, 29, 0, 30, 0, 0, 21, 32, 0, 0, 0, 17, 0, 0, 0, 36, 0, 37, 50, 38, 0, 26, 0, 10

Offset: 1

Author

Santi Spadaro, Jun 24 2002

Keywords

• nonn

Comments

a(n)=0 for prime n>3. - T. D. Noe, Sep 06 2005

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16848

Programs

Mathematica

a[n_] := Mod[Apply[Plus, Union[Table[Mod[i^2, n], {i, 1, n}]]], n]

PARI

A071782(n) = (vecsum(Set(vector(n,i,(i^2)%n)))%n); \\ Antti Karttunen, Feb 18 2023