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A063454
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Number of solutions to x^3 + y^3 = z^3 mod n.
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12
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1, 4, 9, 20, 25, 36, 55, 112, 189, 100, 121, 180, 109, 220, 225, 448, 289, 756, 487, 500, 495, 484, 529, 1008, 725, 436, 2187, 1100, 841, 900, 1081, 2048, 1089, 1156, 1375, 3780, 973, 1948, 981, 2800, 1681, 1980, 1513, 2420, 4725, 2116, 2209, 4032
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OFFSET
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1,2
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COMMENTS
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Equivalently, the number of solutions to x^3 + y^3 + z^3 == 0 (mod n). - Andrew Howroyd, Jul 18 2018
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LINKS
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PROG
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(PARI) a(n)={my(p=Mod(sum(i=0, n-1, x^(i^3%n)), 1-x^n)); polcoeff(lift(p^3), 0)} \\ Andrew Howroyd, Jul 18 2018
(Python)
ndict = {}
for i in range(n):
m = pow(i, 3, 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]
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CROSSREFS
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KEYWORD
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nonn,mult
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AUTHOR
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Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 25 2001
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EXTENSIONS
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STATUS
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approved
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