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.

A036503 Denominator of n^(n-2)/n!.

Original entry on oeis.org

1, 2, 2, 3, 24, 5, 720, 315, 4480, 567, 3628800, 1925, 479001600, 868725, 14350336, 638512875, 20922789888000, 14889875, 6402373705728000, 14849255421, 7567605760000, 17717861581875, 1124000727777607680000, 2505147019375
Offset: 1

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Keywords

Comments

Denominators of coefficient in LambertW(x) power series, where LambertW(x) is the transcendental function satisfying LambertW(x)*exp( LambertW(x) )=x. - Benoit Cloitre, May 08 2002
Absolute value of denominator of the coefficient of 1/(n*x-1) in the partial fraction decomposition of 1/(x-1)*1/(2*x-1)*...*1/(n*x-1). [Joris Roos (jorisr(AT)gmx.de), Aug 02 2009]

Examples

			1, 1/2, 1/2, 2/3, 25/24, 9/5, 2401/720, 2048/315, 59049/4480, 15625/567, 214358881/3628800, ...
		

Crossrefs

Programs

  • Magma
    [Denominator(n^(n - 2)/Factorial(n)): n in [1..50]]; // G. C. Greubel, Nov 14 2017
  • Mathematica
    Denominator[Table[n^(n - 2)/n!, {n, 1, 50}]] (* G. C. Greubel, Nov 14 2017 *)
  • PARI
    for(n=1, 50, print1(denominator(n^(n-2)/n!), ", ")) \\ G. C. Greubel, Nov 14 2017
    

A227831 Numerators of coefficients in Taylor series for LambertW(x).

Original entry on oeis.org

0, 1, -1, 3, -8, 125, -54, 16807, -16384, 531441, -156250, 2357947691, -2985984, 1792160394037, -7909306972, 320361328125, -35184372088832, 2862423051509815793, -5083731656658, 5480386857784802185939, -32000000000000000, 41209797661291758429, -244636361793658185164
Offset: 0

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Author

N. J. A. Sloane, Aug 01 2013

Keywords

Comments

The denominators are 1, 1, 1, 2, 3, 24, 5, 720, 315, 4480, 567, 3628800, 1925, ..., which is A095996 prefixed by 1.

Examples

			0, 1, -1, 3/2, -8/3, 125/24, -54/5, 16807/720, -16384/315, 531441/4480, -156250/567, 2357947691/3628800, -2985984/1925, ...
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, Addison-Wesley, 2nd ed., Eq. (5.66).
  • M. Kauers and P. Paule, The Concrete Tetrahedron, Springer 2011, p. 34.

Crossrefs

Cf. A095996. See also A036504/A036503.

Programs

  • Maple
    series(LambertW(x),x,30); # N. J. A. Sloane, Jan 08 2021
  • Mathematica
    Numerator[CoefficientList[Series[LambertW[x], {x, 0, 22}], x]] (* Mats Granvik, Nov 24 2013 *)
    Numerator[CoefficientList[InverseSeries[Series[x/Sum[((-x)^n)/Factorial[n], {n, 0, 22}], {x, 0, 22}]], x]] (* Mats Granvik, Nov 24 2013 *)

Formula

Numerators of series reversion of x/(Sum_{n=0..infinity} ((-x)^n)/n!). - Mats Granvik, Nov 24 2013

A036502 Numerator of n^(n-2)/n!.

Original entry on oeis.org

1, 1, 1, 2, 25, 9, 2401, 2048, 59049, 15625, 214358881, 248832, 137858491849, 564950498, 21357421875, 2199023255552, 168377826559400929, 282429536481, 288441413567621167681, 1600000000000000, 1962371317204369449, 11119834626984462962
Offset: 1

Views

Author

Keywords

Examples

			1, 1/2, 1/2, 2/3, 25/24, 9/5, 2401/720, 2048/315, 59049/4480, 15625/567, 214358881/3628800, ...
		

Crossrefs

Showing 1-3 of 3 results.