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.

A377676 a(n) is the number of divisors of n^n - n.

Original entry on oeis.org

2, 8, 18, 40, 24, 120, 48, 336, 80, 192, 72, 1920, 48, 288, 23040, 1728, 36, 10240, 72, 7680, 432, 240, 384, 32256, 640, 49152, 2016, 3840, 96, 193536, 1152, 22528, 1152, 4608, 1327104, 1638400, 96, 7680, 9216, 4128768, 384, 294912, 72, 23040, 30720, 576
Offset: 2

Views

Author

Sean A. Irvine, Nov 03 2024

Keywords

Links

Crossrefs

Cf. A000005, A061190, A334167, A372229, A372599, A377672, A377675, A377677, A377678.

Programs

  • Mathematica
    a[n_] := DivisorSigma[0, n^n - n]; Array[a, 45, 2] (* Amiram Eldar, Nov 04 2024 *)
  • PARI
    a(n) = numdiv(n^n-n);

Formula

a(n) = A000005(A061190(n)).

A377677 a(n) is the sum of the divisors of n^n - n.

Original entry on oeis.org

3, 60, 728, 10416, 116064, 2837120, 36990720, 1452853584, 27615698352, 965243666880, 23861701899840, 1355882884941312, 20758574413420992, 1604569397488307712, 93340493714183159808, 3135286584767445151680, 90560273718863022770592, 8284620870197084160000000
Offset: 2

Views

Author

Sean A. Irvine, Nov 03 2024

Keywords

Links

Crossrefs

Cf. A000203, A061190, A366819, A377673, A377675, A377676, A377678.

Programs

  • Mathematica
    a[n_] := DivisorSigma[1, n^n - n]; Array[a, 20, 2] (* Amiram Eldar, Nov 04 2024 *)
  • PARI
    a(n) = sigma(n^n-n);

Formula

a(n) = A000203(A061190(n)).

A377678 a(n) = phi(n^n - n) where phi is the Euler totient function.

Original entry on oeis.org

1, 8, 72, 768, 12400, 217728, 7112448, 94371840, 2594586816, 69139840000, 2584376931840, 58779453358080, 4367959006806720, 100089965305451520, 3251736576000000000, 200445251536048619520, 12343971160877345120064, 422076038504126628593664
Offset: 2

Views

Author

Sean A. Irvine, Nov 03 2024

Keywords

Links

Crossrefs

Cf. A000010, A061190, A366821, A372229, A372599, A377674, A377675, A377676, A377677.

Programs

  • Mathematica
    a[n_] := EulerPhi[n^n - n]; Array[a, 20, 2] (* Amiram Eldar, Nov 04 2024 *)
  • PARI
    a(n) = eulerphi(n^n-n);

Formula

a(n) = A000010(A061190(n)).
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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