A288105 Number of solutions to x^10 + y^10 = z^10 mod n.

1, 4, 9, 24, 25, 36, 49, 192, 99, 100, 201, 216, 169, 196, 225, 1024, 289, 396, 361, 600, 441, 804, 529, 1728, 3125, 676, 1377, 1176, 841, 900, 601, 6144, 1809, 1156, 1225, 2376, 1369, 1444, 1521, 4800, 1201, 1764, 1849, 4824, 2475, 2116, 2209, 9216, 2695, 12500

Offset: 1

Author

Seiichi Manyama, Jun 05 2017

Keywords

• nonn
• mult

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Seiichi Manyama)

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), A288102 (k=7), A288103 (k=8), A288104 (k=9), this sequence (k=10).

Programs

Mathematica

Table[cnt=0; Do[If[Mod[x^10 + y^10 - z^10, n]==0, cnt++], {x, 0, n-1}, {y, 0, n-1}, {z, 0, n-1}]; cnt, {n, 50}] (* Vincenzo Librandi, Jul 18 2018 *)

Python

def A288105(n):
    ndict = {}
    for i in range(n):
        m = pow(i,10,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

Extensions

Keyword:mult added by Andrew Howroyd, Jul 17 2018