A121278 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

A121278

Number of distinct integers of the form (x^n + y^n) mod n^2.

1, 3, 5, 3, 13, 9, 19, 5, 15, 15, 51, 9, 73, 30, 65, 9, 113, 21, 163, 9, 25, 63, 265, 15, 65, 57, 45, 30, 281, 45, 391, 17, 255, 123, 247, 21, 577, 165, 65, 15, 841, 27, 757, 63, 195, 234, 1105, 27, 133, 75, 565, 30, 1249, 57, 65, 50, 95, 339, 929, 27, 1321, 408, 75, 33, 949

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

It is enough to take x,y from {0,1,...,n-1}. Therefore a(n)<=n*(n+1)/2.

LINKS

Table of n, a(n) for n=1..65.

PROG

(PARI) { a(n) = my(S, t); S=Set(); for(x=0, n-1, for(y=x, n-1, t=lift(Mod(x, n^2)^n+Mod(y, n^2)^n); S=setunion(S, [t]); ); ); #S }

(PARI) a(n) = #setbinop((x, y)->Mod(x, n^2)^n+Mod(y, n^2)^n, [0..n-1]); \\ Michel Marcus, Oct 16 2023

CROSSREFS

Sequence in context: A336806 A023583 A266603 * A023587 A172003 A244801