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 1-4 of 4 results.

A101613 (2n)! * Sum[k=n..2n, 1/k].

Original entry on oeis.org

3, 26, 684, 35664, 3068640, 392722560, 69878833920, 16484477184000, 4976250951168000, 1870345490614272000, 856314330237628416000, 469109144339151224832000, 302956190548293037916160000
Offset: 1

Views

Author

Ralf Stephan, Dec 10 2004

Keywords

Crossrefs

Cf. A101609, A101610, A101611, A101612, A000254, A046673, A052517.

A101609 a(n) = n! * Sum_{k=1..floor(n/2)} 1/k.

Original entry on oeis.org

0, 2, 6, 36, 180, 1320, 9240, 84000, 756000, 8285760, 91143360, 1173553920, 15256200960, 226040855040, 3390612825600, 56865153945600, 966707617075200, 18112111963545600, 344130127307366400, 7125892746964992000
Offset: 1

Views

Author

Ralf Stephan, Dec 10 2004

Keywords

Crossrefs

Cf. A101610, A101611, A101612, A101613, A000254, A046673, A052517.

Programs

  • Mathematica
    Table[ n! HarmonicNumber[ Floor[ n/2]], {n, 20}] (* Robert G. Wilson v, Dec 11 2004 *)

Formula

a(1) = 0, a(n) = a(n-1)*n + (1 + (-1)^n)*(n-1)!. - Daniel Suteu, Feb 06 2017

A101610 n! * Sum[k=1..ceiling(n/2), 1/k].

Original entry on oeis.org

1, 2, 9, 36, 220, 1320, 10500, 84000, 828576, 8285760, 97796160, 1173553920, 16145775360, 226040855040, 3554072121600, 56865153945600, 1006228442419200, 18112111963545600, 356294637348249600
Offset: 1

Views

Author

Ralf Stephan, Dec 10 2004

Keywords

Crossrefs

Cf. A101609, A101611, A101612, A101613, A000254, A046673, A052517.

Programs

  • Mathematica
    Table[n!Sum[1/k,{k,1,Ceiling[n/2]}],{n,20}]  (* Harvey P. Dale, Apr 25 2011 *)

A101612 n! * Sum[k=floor(n/2)..n, 1/k].

Original entry on oeis.org

3, 11, 26, 154, 684, 5508, 35664, 361296, 3068640, 37383840, 392722560, 5584394880, 69878833920, 1135360800000, 16484477184000, 301158902016000, 4976250951168000, 100951141777920000, 1870345490614272000
Offset: 2

Views

Author

Ralf Stephan, Dec 10 2004

Keywords

Crossrefs

Cf. A101609, A101610, A101611, A101613, A000254, A046673, A052517.
Showing 1-4 of 4 results.

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

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