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.

A321827 a(n) = Sum_{d|n, d==1 (mod 4)} d^11 - Sum_{d|n, d==3 (mod 4)} d^11.

Original entry on oeis.org

1, 1, -177146, 1, 48828126, -177146, -1977326742, 1, 31380882463, 48828126, -285311670610, -177146, 1792160394038, -1977326742, -8649707208396, 1, 34271896307634, 31380882463, -116490258898218, 48828126, 350275523038332, -285311670610
Offset: 1

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Author

N. J. A. Sloane, Nov 24 2018

Keywords

Crossrefs

Column k=11 of A322143.
Cf. A321543 - A321565, A321807 - A321836 for similar sequences.
Cf. A000265.

Programs

  • Mathematica
    s[n_, r_] := DivisorSum[n, #^11 &, Mod[#, 4] == r &]; a[n_] := s[n, 1] - s[n, 3]; Array[a, 30] (* Amiram Eldar, Nov 26 2018 *)
    f[p_, e_] := If[Mod[p, 4] == 1, ((p^11)^(e+1)-1)/(p^11-1), ((-p^11)^(e+1)-1)/(-p^11-1)]; f[2, e_] := 1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 60] (* Amiram Eldar, Sep 27 2023 *)
  • PARI
    apply( A321828(n)=sumdiv(n>>valuation(n,2),d,(2-d%4)*d^11), [1..40]) \\ M. F. Hasler, Nov 26 2018

Formula

a(n) = a(A000265(n)). - M. F. Hasler, Nov 26 2018
G.f.: Sum_{k>=1} (-1)^(k-1)*(2*k - 1)^11*x^(2*k-1)/(1 - x^(2*k-1)). - Ilya Gutkovskiy, Dec 06 2018
Multiplicative with a(2^e) = 1, and for an odd prime p, ((p^11)^(e+1)-1)/(p^11-1) if p == 1 (mod 4) and ((-p^11)^(e+1)-1)/(-p^11-1) if p == 3 (mod 4). - Amiram Eldar, Sep 27 2023
a(n) = Sum_{d|n} d^11*sin(d*Pi/2). - Ridouane Oudra, Sep 08 2024