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 1-6 of 6 results.

A226282 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],1)*C([(n+1)/2],1).

Original entry on oeis.org

0, 1, 4, 16, 72, 324, 1728, 9216, 57600, 360000, 2592000, 18662400, 152409600, 1244678400, 11379916800, 104044953600, 1053455155200, 10666233446400, 118513704960000, 1316818944000000, 15933509222400000, 192795461591040000, 2523867860828160000, 33039724723568640000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 2 odd displacements.
Column 2 of A226288.
Column k=2 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

Crossrefs

Cf. A145893, A145894, A226288.

Programs

  • Mathematica
    Table[Floor[n/2]!Floor[(n+1)/2]!Binomial[Floor[n/2],1]Binomial[Floor[(n+1)/2],1],{n,30}] (* Harvey P. Dale, Aug 05 2023 *)

A226283 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],2)*C([(n+1)/2],2).

Original entry on oeis.org

0, 0, 0, 4, 36, 324, 2592, 20736, 172800, 1440000, 12960000, 116640000, 1143072000, 11202105600, 119489126400, 1274550681600, 14748372172800, 170659735142400, 2133246689280000, 26665583616000000, 358503957504000000, 4819886539776000000, 69406366172774400000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 4 odd displacements.
Column 3 of A226288.
Column k=4 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

Crossrefs

Cf. A145893, A145894, A226288.

Programs

  • Mathematica
    a[n_]:=(Floor[n/2])!(Floor[(n+1)/2])!Binomial[Floor[n/2],2]Binomial[Floor[(n+1)/2],2]; Array[a,23] (* Stefano Spezia, Jul 12 2024 *)

A226284 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],3)*C([(n+1)/2],3).

Original entry on oeis.org

0, 0, 0, 0, 0, 36, 576, 9216, 115200, 1440000, 17280000, 207360000, 2540160000, 31116960000, 398297088000, 5098202726400, 68825736806400, 929147446886400, 13273534955520000, 189621927936000000, 2868031660032000000, 43378978857984000000, 694063661727744000000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 6 odd displacements.
Column 4 of A226288.
Column k=6 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

Crossrefs

Cf. A145893, A145894, A226288.

Programs

  • Mathematica
    Table[Floor[n/2]!Floor[(n+1)/2]!Binomial[Floor[n/2],3]Binomial[Floor[ (n+1)/2], 3],{n,30}] (* Harvey P. Dale, Dec 12 2018 *)

A226285 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],4)*C([(n+1)/2],4).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 576, 14400, 360000, 6480000, 116640000, 1905120000, 31116960000, 497871360000, 7965941760000, 129048256512000, 2090581755494400, 34843029258240000, 580717154304000000, 10038110810112000000, 173515915431936000000, 3123286477774848000000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 8 odd displacements.
Column 5 of A226288.
Column k=8 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

Crossrefs

Cf. A145893, A145894, A226288.

Programs

  • Mathematica
    a[n_]:= Floor[n/2]!*Floor[(n+1)/2]!*Binomial[Floor[n/2],4]*Binomial[Floor[(n+1)/2],4]; Array[a,21] (* Stefano Spezia, Jul 12 2024 *)

A226286 [n/2]!*[(n+1)/2]!*C([n/2],5)*C([(n+1)/2],5).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 14400, 518400, 18662400, 457228800, 11202105600, 238978252800, 5098202726400, 103238605209600, 2090581755494400, 41811635109888000, 836232702197760000, 16864026160988160000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 10 odd displacements.
Column 6 of A226288.
Column k=10 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

A226287 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],6)*C([(n+1)/2],6).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 518400, 25401600, 1244678400, 39829708800, 1274550681600, 34412868403200, 929147446886400, 23228686172160000, 580717154304000000, 14053355134156800000, 340091194246594560000
Offset: 1

Views

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Keywords

Comments

Number of permutations of n elements with 12 odd displacements.
Column 7 of A226288.
Column k=12 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

Showing 1-6 of 6 results.

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

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