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 1-10 of 11 results. Next

A005118 Number of simple allowable sequences on 1..n containing the permutation 12...n.

Original entry on oeis.org

1, 1, 1, 2, 16, 768, 292864, 1100742656, 48608795688960, 29258366996258488320, 273035280663535522487992320, 44261486084874072183645699204710400, 138018895500079485095943559213817088756940800
Offset: 0

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Author

Keywords

Comments

For n >= 2 by the hook length formula a(n) is also the number of Young tableaux of size 1+2+...+(n-1) = n*(n-1)/2 that correspond to the partition (1,2,...n-1), i.e., triangular Young tableaux. For example, for n=5 the shape of the tableau is xxxx / xxx / xx / x. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 04 2001
Also, a(n) is the degree of the symplectic Grassmannian, the projective variety of all maximal isotropic subspaces in a complex vector space of dimension 2n-2 with a symplectic form. See Hiller's paper. - Burt Totaro (b.totaro(AT)dpmms.cam.ac.uk), Oct 29 2002
Also, for n >= 2, a(n) is the number of maximal chains in the poset of Dyck paths ordered by inclusion. - Jennifer Woodcock (Jennifer.Woodcock(AT)ugdsb.on.ca), May 21 2008
a(n) is the number of minimal decompositions of the "flip" permutation n(n-1)..21 in terms of the n-1 standard Coxeter generators (i i+1) ("reduced decompositions", cf. Stanley). As such, it is also the number of positive n-strand braid words representing the Garside braid Delta(n) (the half-turn) (cf. Epstein's book, lemma 9.1.14). - Maxime Bourrigan, Apr 04 2011
For n >= 1, the normalized volume of the subpolytope of the Birkhoff polytope obtained by taking the convex hull of all (2n)x(2n) permutation matrices corresponding to alternating permutations that also avoid the pattern 123. - Robert Davis, Dec 04 2016

References

  • D. B. A. Epstein with J. W. Cannon, D. F. Holt, S. V. F. Levy, M. S. Paterson and W. P. Thurston, Word Processing in Groups, Jones and Bartlett Publishers, Boston, MA, 1992. xii+330 pp.
  • J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.
  • G. Kreweras, Sur un problème de scrutin à plus de deux candidats, Publications de l'Institut de Statistique de l'Université de Paris, 26 (1981), 69-87.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    A005118 := proc(n) local i; binomial(n,2)!/product( (2*i+1)^(n-i-1), i=0..n-2 ); end;
  • Mathematica
    Table[Binomial[n, 2]!/Product[(2*i + 1)^(n - i - 1), {i, 0, n - 2}], {n, 0, 10}] (* T. D. Noe, May 29 2012 *)

Formula

a(n) = C(n, 2)!/(1^{n-1} * 3^{n-2} *...* (2n-3)^1 ).
a(n) = (n*(n-1)/2)!/A057863(n-1) (n>=1). - Emeric Deutsch, May 21 2004
a(n) = A153452(A002110(n-1)). - Naohiro Nomoto, Jan 01 2009
From Alois P. Heinz, Nov 18 2012: (Start)
a(n+1) = A219272(A000217(n),n) = A219274(A000217(n),n) = A219311(A000217(n),n).
a(n) = A193536(n,A000217(n-1)) = A193629(n,A000217(n-1)). (End)
a(n) ~ sqrt(Pi) * n^(n^2/2-n/2+23/24) * exp(n^2/4-n/2+7/24) / (A^(1/2) * 2^(n^2-n/2-7/24)), where A = 1.2824271291... is the Glaisher-Kinkelin constant (see A074962). - Vaclav Kotesovec, Nov 13 2014

Extensions

Citation corrected by Matthew J. Samuel, Feb 01 2011

A218293 Number of standard Young tableaux with shapes corresponding to partitions into distinct parts.

Original entry on oeis.org

1, 1, 1, 3, 4, 10, 31, 70, 190, 561, 2191, 6226, 22683, 74152, 283349, 1211354, 4572672, 18844177, 77585825, 327472752, 1418056071, 7083303437, 31251988918, 153456264178, 723293387594, 3596567095155, 17360616601051, 89955643932801, 486526881887485, 2551613423040841, 14029592127656040, 76756835252971657, 428044848852530252
Offset: 0

Views

Author

Joerg Arndt, Oct 25 2012

Keywords

Crossrefs

Cf. A000085 (standard Young tableaux for all shapes).
Diagonal of A219272, row sums of A219274, A219311. - Alois P. Heinz, Nov 17 2012
Cf. A225121 (tableaux with shapes corresponding to partitions into distinct parts with minimal difference 2).

Programs

  • Maple
    h:= proc(l) local n; n:=nops(l); add(i, i=l)!/mul(mul(1+l[i]-j+
          add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
        end:
    g:= proc(n, i, l) local s; s:=i*(i+1)/2;
          `if`(n=s, h([l[], seq(i-j, j=0..i-1)]), `if`(n>s, 0,
           g(n, i-1, l)+ `if`(i>n, 0, g(n-i, i-1, [l[], i]))))
        end:
    a:= n-> g(n, n, []):
    seq(a(n), n=0..40);  # Alois P. Heinz, Nov 08 2012
  • Mathematica
    h[l_List] := Module[{n=Length[l]}, Total[l]!/Product[Product[1+l[[i]]-j + Sum[ If[ l[[k]] >= j, 1, 0], {k, i+1, n}], {j, 1, l[[i]]}], {i, 1, n}]]; g[n_, i_, l_List] := Module[{s=i*(i+1)/2}, If[n == s, h[Join[l, Table[i-j, {j, 0, i-1}]]], If[n > s, 0, g[n, i-1, l] + If[i>n, 0, g[n-i, i-1, Append[l, i]]]]]]; a[n_] := g[n, n, {}]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 18 2015, after Alois P. Heinz *)

A219320 Number of standard Young tableaux for partitions of n into exactly 7 distinct parts.

Original entry on oeis.org

48608795688960, 295284192952320, 2741894304901440, 18535141513347030, 134524383564933720, 851007098153745060, 5822391651578231460, 37395948352954386420, 238518115727229867660, 1501480486903096567740, 9413700760748972005500, 58167406634979463024710
Offset: 28

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=7 of A219311.
Cf. A218293.

A047171 Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= (n-1)/2.

Original entry on oeis.org

0, 0, 0, 2, 3, 9, 14, 34, 55, 125, 209, 461, 791, 1715, 3002, 6434, 11439, 24309, 43757, 92377, 167959, 352715, 646645, 1352077, 2496143, 5200299, 9657699, 20058299, 37442159, 77558759, 145422674, 300540194, 565722719, 1166803109, 2203961429, 4537567649
Offset: 0

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Author

Keywords

Comments

For n>=1 the number of standard Young tableaux with shapes corresponding to partitions into two distinct parts. - Joerg Arndt, Oct 25 2012

Crossrefs

Column k=2 of A219311. - Alois P. Heinz, Nov 17 2012

Programs

  • Magma
    [0] cat [Binomial(n, Floor((n-1)/2))-1: n in [1..40]]; // Vincenzo Librandi, Jul 03 2015
  • Maple
    a:= n-> binomial(n, iquo(n-1,2))-1:
    seq(a(n), n=0..40);  # Alois P. Heinz, Nov 17 2012
  • Mathematica
    a[n_] := Binomial[n, Floor[(n-1)/2]]-1; a[0] = 0; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Jul 03 2015 *)

Formula

a(n) = A037952(n) - 1. Proof by Ira Gessel: Write down the number of such subsets with k elements <= (n-1)/2 as a product of two binomial coefficients, then evaluate the sum using Vandermonde's theorem.

A219316 Number of standard Young tableaux for partitions of n into exactly 3 distinct parts.

Original entry on oeis.org

16, 35, 134, 435, 1213, 3454, 10484, 28249, 80302, 231895, 638406, 1798515, 5170279, 14361074, 40675562, 116701060, 327587324, 931854890, 2678822398, 7577813175, 21658478151, 62401989636, 177658786252, 509822342794, 1472491312385, 4213745453731, 12134760359950
Offset: 6

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=3 of A219311.
Cf. A218293.

Formula

a(n) ~ 3^(n+3/2) / (2*sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Aug 31 2014

A219317 Number of standard Young tableaux for partitions of n into exactly 4 distinct parts.

Original entry on oeis.org

768, 2310, 11407, 44187, 200044, 680160, 2769674, 9826918, 38483206, 135059866, 515249581, 1829452107, 6941537898, 24678730371, 92755537994, 333149285650, 1252530682570, 4513808634840, 16936935284163, 61508180909442, 231189178986445, 843098892380280
Offset: 10

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=4 of A219311.
Cf. A218293.

Formula

a(n) ~ 2^(2*n+5) / (Pi*n^3). - Vaclav Kotesovec, Sep 13 2014

A219318 Number of standard Young tableaux for partitions of n into exactly 5 distinct parts.

Original entry on oeis.org

292864, 1153152, 7194434, 33888582, 177959434, 861962968, 4036054898, 18519351642, 85808400115, 389017226948, 1778061013340, 7967135309510, 35973133665285, 161398383117645, 726152765571840, 3256479005867430, 14629885404315411, 65641088599945380
Offset: 15

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=5 of A219311.
Cf. A218293.

A219319 Number of standard Young tableaux for partitions of n into exactly 6 distinct parts.

Original entry on oeis.org

1100742656, 5462865408, 42035926724, 238839304110, 1477773782690, 8119282473120, 49406279584740, 259405071568305, 1468158383705685, 7798557001165665, 42744495396935010, 224697430361576340, 1226112009886575180, 6397760480647576200, 34422065224987469772
Offset: 21

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=6 of A219311.
Cf. A218293.

A219321 Number of standard Young tableaux for partitions of n into exactly 8 distinct parts.

Original entry on oeis.org

29258366996258488320, 212593716124699852800, 2338077979922915527680, 18541315347775500731880, 156386347073221236234900, 1136852065645214098726260, 8834800018708598317055880, 63128042819798223843289680, 473458147812239316816345390, 3325190851643455231559076330
Offset: 36

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=8 of A219311.
Cf. A218293.

A219322 Number of standard Young tableaux for partitions of n into exactly 9 distinct parts.

Original entry on oeis.org

273035280663535522487992320, 2329440559042398325938585600, 29867922172910654180714311680, 274273837545154589560694664960, 2661165012109500556315841832780, 22087643957707583932955480283900, 194567964473214023234175600529800, 1559754564113482833062794519391700
Offset: 45

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Crossrefs

Column k=9 of A219311.
Cf. A218293.
Showing 1-10 of 11 results. Next