A305212 a(n) = n - A305211(n).

0, 0, 0, 0, 0, 0, 2, 0, 4, 0, 0, 0, 0, 4, 0, 0, 0, 8, 0, 0, 6, 0, 0, 0, 0, 0, 12, 8, 0, 0, 0, 0, 0, 0, 10, 16, 0, 0, 0, 0, 0, 12, 0, 0, 20, 0, 0, 0, 14, 0, 0, 0, 0, 24, 0, 16, 0, 0, 0, 0, 0, 0, 38, 0, 0, 0, 0, 0, 0, 20, 0, 32, 0, 0, 0, 0, 22, 0, 0, 0, 36, 0, 0

Offset: 1

Author

Jack Zhang, May 27 2018

Keywords

• nonn

Comments

Number of integers d from 0 to n-1 such that x^3 + y^3 == d (mod n) has no solutions in integers.

Crossrefs

Cf. A305211.

Programs

PARI

a(n) = my(v=[]); for (x=1, n, for (y=1, n, v = concat(v, Mod(x, n)^3 + Mod(y, n)^3))); n - #Set(v); \\ Michel Marcus, Jul 10 2018

Python

[n-len(set((pow(x,3,n)+pow(y,3,n))%n for x in range(n) for y in range(x+1))) for n in range(1,51)]

Extensions

a(50)-a(83) from Jon E. Schoenfield, May 28 2018