cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A231563 a(n) = f(1)^n + ... + f(n)^n (mod n) where f(i)=i if gcd(i,n)=1 and f(i)=0 otherwise.

Original entry on oeis.org

0, 1, 0, 2, 0, 2, 0, 4, 0, 0, 0, 4, 0, 0, 0, 8, 0, 6, 0, 8, 0, 0, 0, 8, 0, 0, 0, 0, 0, 20, 0, 16, 0, 0, 0, 12, 0, 0, 0, 16, 0, 12, 0, 0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 18, 0, 0, 0, 0, 0, 16, 0, 0, 0, 32, 0, 44, 0, 0, 0, 0, 0, 24, 0, 0, 0, 0, 0, 0, 0, 32, 0, 0
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    S[n_] :=  Mod[Sum[If[GCD[i, n] == 1, PowerMod[i, n, n], 0], {i, 1, n}], n]; Array[S,100]
  • PARI
    f(i, n) = if (gcd(i, n) == 1, i, 0);
    a(n) = lift(sum(k=1, n, Mod(f(k, n), n)^n)); \\ Michel Marcus, Jul 16 2017

Formula

a(n) = A308481(n) mod n. - Seiichi Manyama, Feb 11 2021

A231564 Numbers such that A231563(n)=0.

Original entry on oeis.org

1, 3, 5, 7, 9, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 26, 27, 28, 29, 31, 33, 34, 35, 37, 38, 39, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 85, 86, 87, 88
Offset: 1

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Author

Keywords

Comments

This sequence contains the odd primes.

Crossrefs

Programs

  • Mathematica
    S[n_] := Mod[Sum[If[GCD[i, n] == 1, PowerMod[i, n, n], 0], {i, 1, n}], n];Select[Range[100],S[#]==0&]

A263014 a(n) = Sum_{0 < a, b <= n and gcd(a^2 + b^2, n) = 1} (a + bi)^n (mod n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 0, 0, 0, 0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 48, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 64, 0, 0, 0, 0
Offset: 1

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Author

Keywords

Comments

Sum of the n-th powers of the invertible elements of Z[i]/nZ[i].

Crossrefs

See A263016 for indices where this is nonzero.
See A290287 for the nonzero values.

Programs

  • Mathematica
    Sp[n_, k_] := Mod[Sum[If[GCD[a^2 + b^2, n] == 1, PowerMod[(a + b I), k, n], 0], {a, n}, {b, n}], n]; Table[ Sp[n, n] , {n, 1, 74}]
Showing 1-3 of 3 results.