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.

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A232181 First bisection of harmonic numbers (denominators).

Original entry on oeis.org

1, 6, 60, 140, 2520, 27720, 360360, 360360, 12252240, 77597520, 5173168, 118982864, 8923714800, 80313433200, 2329089562800, 72201776446800, 13127595717600, 13127595717600, 485721041551200, 485721041551200, 19914562703599200, 122332313750680800
Offset: 1

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Keywords

Comments

Denominator of H(2*n-1), where H(n) = Sum_{k=1..n} 1/k.

Crossrefs

Cf. A002805, A232180 (numerators).

Programs

  • Magma
    [Denominator(HarmonicNumber(2*n-1)): n in [1..30]]; // Bruno Berselli, Nov 20 2013
  • Mathematica
    a[n_] := HarmonicNumber[2*n-1] // Denominator; Table[a[n], {n, 1, 25}]

Formula

a(n) ~ exp(2n).
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