OFFSET
1,2
COMMENTS
Equivalently, the number of solutions to x^9 + y^9 + z^9 == 0 (mod n). - Andrew Howroyd, Jul 17 2018
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Seiichi Manyama)
MATHEMATICA
Table[cnt=0; Do[If[Mod[x^9 + y^9 - z^9, n]==0, cnt++], {x, 0, n-1}, {y, 0, n-1}, {z, 0, n-1}]; cnt, {n, 50}] (* Vincenzo Librandi, Jul 18 2018 *)
PROG
(PARI) a(n)={my(p=Mod(sum(i=0, n-1, x^lift(Mod(i, n)^9)), 1-x^n)); polcoeff(lift(p^3), 0)} \\ Andrew Howroyd, Jul 17 2018
(Python)
def A288104(n):
ndict = {}
for i in range(n):
m = pow(i, 9, n)
if m in ndict:
ndict[m] += 1
else:
ndict[m] = 1
count = 0
for i in ndict:
ni = ndict[i]
for j in ndict:
k = (i+j) % n
if k in ndict:
count += ni*ndict[j]*ndict[k]
return count # Chai Wah Wu, Jun 05 2017
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Seiichi Manyama, Jun 05 2017
EXTENSIONS
Keyword:mult added by Andrew Howroyd, Jul 17 2018
STATUS
approved