A288102 Number of solutions to x^7 + y^7 = z^7 mod n.

1, 4, 9, 20, 25, 36, 49, 112, 99, 100, 121, 180, 169, 196, 225, 704, 289, 396, 361, 500, 441, 484, 529, 1008, 725, 676, 1377, 980, 589, 900, 961, 4864, 1089, 1156, 1225, 1980, 1369, 1444, 1521, 2800, 1681, 1764, 4999, 2420, 2475, 2116, 2209, 6336, 10633, 2900

Offset: 1

Author

Seiichi Manyama, Jun 05 2017

Keywords

• nonn
• mult

Comments

Equivalently, the number of solutions to x^7 + y^7 + z^7 == 0 (mod n). - Andrew Howroyd, Jul 17 2018

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..1000

Crossrefs

Number of solutions to x^k + y^k = z^k mod n: A062775 (k=2), A063454 (k=3), A288099 (k=4), A288100 (k=5), A288101 (k=6), this sequence (k=7), A288103 (k=8), A288104 (k=9), A288105 (k=10).

Programs

PARI

a(n)={my(p=Mod(sum(i=0, n-1, x^lift(Mod(i,n)^7)), 1-x^n)); polcoeff(lift(p^3), 0)} \\ Andrew Howroyd, Jul 17 2018

Extensions

Keyword:mult added by Andrew Howroyd, Jul 17 2018