A376757 Number of pairs 0 <= x <= y <= n-1 such that x^3 == y^3 (mod n).

1, 2, 3, 5, 5, 6, 13, 14, 18, 10, 11, 15, 25, 26, 15, 28, 17, 36, 37, 25, 39, 22, 23, 42, 35, 50, 81, 71, 29, 30, 61, 72, 33, 34, 65, 99, 73, 74, 75, 70, 41, 78, 85, 55, 90, 46, 47, 84, 112, 70, 51, 137, 53, 162, 55, 218, 111, 58, 59, 75, 121, 122, 288, 208, 125, 66, 133, 85, 69, 130, 71, 306, 145, 146, 105, 203, 143, 150, 157

Offset: 1

Author

Tom Duff and N. J. A. Sloane, Oct 06 2024

Keywords

• nonn

Comments

A087786 includes pairs (x,y) with x>y (which are excluded from the present sequence).

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000086, A087786, A046530, A290731, A376202, A376203, A376755, A376756.

Programs

PARI

a(n) = sum(x=0, n-1, sum(y=x, n-1, Mod(x, n)^3 == Mod(y, n)^3)); \\ Michel Marcus, Oct 06 2024

Python

from collections import Counter
def A376757(n): return sum(d*(d+1)>>1 for d in Counter(pow(x,3,n) for x in range(n)).values()) # Chai Wah Wu, Oct 06 2024