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A305212 a(n) = n - A305211(n). 1
0, 0, 0, 0, 0, 0, 2, 0, 4, 0, 0, 0, 0, 4, 0, 0, 0, 8, 0, 0, 6, 0, 0, 0, 0, 0, 12, 8, 0, 0, 0, 0, 0, 0, 10, 16, 0, 0, 0, 0, 0, 12, 0, 0, 20, 0, 0, 0, 14, 0, 0, 0, 0, 24, 0, 16, 0, 0, 0, 0, 0, 0, 38, 0, 0, 0, 0, 0, 0, 20, 0, 32, 0, 0, 0, 0, 22, 0, 0, 0, 36, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

Number of integers d from 0 to n-1 such that x^3 + y^3 == d (mod n) has no solutions in integers.

LINKS

Table of n, a(n) for n=1..83.

PROG

(Python) [n-len(set((pow(x, 3, n)+pow(y, 3, n))%n for x in range(n) for y in range(x+1))) for n in range(1, 51)]

(PARI) a(n) = my(v=[]); for (x=1, n, for (y=1, n, v = concat(v, Mod(x, n)^3 + Mod(y, n)^3))); n - #Set(v); \\ Michel Marcus, Jul 10 2018

CROSSREFS

Cf. A305211.

Sequence in context: A261162 A218862 A243199 * A104774 A087263 A099894

Adjacent sequences:  A305209 A305210 A305211 * A305213 A305214 A305215

KEYWORD

nonn,changed

AUTHOR

Jack Zhang, May 27 2018

EXTENSIONS

a(50)-a(83) from Jon E. Schoenfield, May 28 2018

STATUS

approved

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Last modified June 5 09:58 EDT 2020. Contains 334840 sequences. (Running on oeis4.)