A376755 a(n) = A376202(6*n+1)/6.

1, 2, 3, 0, 5, 6, 7, 7, 0, 10, 11, 12, 13, 0, 24, 16, 17, 18, 0, 0, 21, 36, 23, 0, 25, 26, 27, 26, 0, 30, 0, 32, 33, 0, 35, 60, 37, 38, 0, 40, 72, 0, 72, 0, 45, 46, 47, 0, 0, 84, 51, 52, 0, 0, 55, 56, 49, 58, 0, 57, 61, 62, 63, 0, 0, 66, 120, 68, 0, 70, 120, 72

Offset: 1

Author

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

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..3470

Crossrefs

Cf. A000086, A046530, A087786, A290731, A376202, A376203, A376756, A376757.

Programs

Python

from math import gcd
def A376755(n):
    c, m = 0, 6*n|1
    for x in range(1,m):
        if gcd(x,m) == 1:
            for y in range(x,m):
                if gcd(y,m)==gcd(z:=x+y,m)==1 and not (w:=z**2-x*y)//gcd(w,x*y*z)%m:
                    c += 1
    return c//6 # Chai Wah Wu, Oct 06 2024

Extensions

a(51)-a(72) from Chai Wah Wu, Oct 06 2024