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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A256194 a(n) = denominator of n!*n^n*Product_{k=0..n} 1/(n*k + n - 1).

Original entry on oeis.org

15, 440, 21945, 277704, 178986115, 215289360, 107174712645, 2019114114160, 5162399729063577, 310327149656160, 264020420256172514935, 555320997799108800, 183986274976015448239875, 7616449380979972355121376, 132186242095677958872242925, 3493664585524176681103200
Offset: 2

Views

Author

Michel Marcus, Mar 19 2015

Keywords

Comments

n!*n^n*Product_{k=0..n} 1/(n*k + n - 1) = Sum_{k=0..n} (-1)^k*binomial(n,k)/(n*k + n - 1) (see arXiv link).

Crossrefs

Cf. A145921 (numerators).

Programs

  • Mathematica
    Table[Denominator[n! n^n Product[1/(n k + n - 1), {k, 0, n}]], {n, 2, 17}] (* Jean-François Alcover, Sep 26 2018 *)
  • PARI
    a(n) = denominator(sum(k=0, n, (-1)^k*binomial(n,k)/(n*k+n-1)));

A364713 a(n) is the numerator of coefficient of x^n in expansion of (1 + x)^(1/n).

Original entry on oeis.org

1, -1, 5, -77, 399, -124729, 81549, -23960365, 283583443, -478398640447, 19740912828, -11911591259019739, 18262332208600, -4514446693068714225, 142267808222130386191, -1912831808055538077885, 39773048560156838355, -43025628065750129034887540875, 86435429204640847578555
Offset: 1

Views

Author

Ilya Gutkovskiy, Aug 04 2023

Keywords

Examples

			1, -1/8, 5/81, -77/2048, 399/15625, -124729/6718464, 81549/5764801, ...
		

Crossrefs

Denominators are A145921.

Programs

  • Mathematica
    Table[SeriesCoefficient[(1 + x)^(1/n), {x, 0, n}], {n, 1, 21}] // Numerator
    Table[Binomial[1/n, n], {n, 1, 21}] // Numerator
  • PARI
    a(n) = numerator(binomial(1/n, n)); \\ Michel Marcus, Aug 05 2023
Showing 1-2 of 2 results.