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A376755
a(n) = A376202(6*n+1)/6.
5
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
1,2
PROG
(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
KEYWORD
nonn
AUTHOR
Tom Duff and N. J. A. Sloane, Oct 06 2024
EXTENSIONS
a(51)-a(72) from Chai Wah Wu, Oct 06 2024
STATUS
approved