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 1-8 of 8 results.

A006335 a(n) = 4^n*(3*n)!/((n+1)!*(2*n+1)!).

Original entry on oeis.org

1, 2, 16, 192, 2816, 46592, 835584, 15876096, 315031552, 6466437120, 136383037440, 2941129850880, 64614360416256, 1442028424527872, 32619677465182208, 746569714888605696, 17262927525017812992, 402801642250415636480, 9474719710174783733760, 224477974671833337692160
Offset: 0

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Author

Keywords

Comments

Number of planar lattice walks of length 3n starting and ending at (0,0), remaining in the first quadrant and using only NE,W,S steps.
Equals row sums of triangle A140136. - Michel Marcus, Nov 16 2014
Number of linear extensions of the poset V x [n], where V is the 3-element poset with one least element and two incomparable elements: see Kreweras and Niederhausen (1981) and Hopkins and Rubey (2020) references. - Noam Zeilberger, May 28 2020

Examples

			G.f. = 1 + 2*x + 16*x^2 + 192*x^3 + 2816*x^4+ 46592*x^5 + 835584*x^6 + ...
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Equals 2^(n-1) * A000309(n-1) for n>1.
Cf. A098272. First row of array A098273.

Programs

  • Magma
    [4^n*Factorial(3*n)/(Factorial(n+1)*Factorial(2*n+1)) : n in [0..20]]; // Wesley Ivan Hurt, Nov 16 2014
    
  • Maple
    A006335:=n->4^n*(3*n)!/((n+1)!*(2*n+1)!): seq(A006335(n), n=0..20); # Wesley Ivan Hurt, Nov 16 2014
  • Mathematica
    aux[i_Integer, j_Integer, n_Integer] := Which[Min[i, j, n] < 0 || Max[i, j] > n, 0, n == 0, KroneckerDelta[i, j, n], True, aux[i, j, n] = aux[-1 + i, j, -1 + n] + aux[i, -1 + j, -1 + n] + aux[1 + i, 1 + j, -1 + n]]; Table[aux[0, 0, 3 n], {n, 0, 25}] (* Manuel Kauers, Nov 18 2008 *)
    Table[(4^n (3 n)! / ((n + 1)! (2 n + 1)!)), {n, 0, 200}] (* Vincenzo Librandi, Nov 17 2014 *)
  • PARI
    {a(n) = if( n<0, 0, 4^n * (3*n)! / ((n+1)! * (2*n+1)!))}; /* Michael Somos, Jan 23 2003 */
    
  • Sage
    def a(n):
        return (4**n * binomial(3 * n, 2 * n)) // ((n + 1) * (2 * n + 1))
    # F. Chapoton, Jun 01 2020

Formula

G.f.: (1/(12*x)) * (hypergeom([ -2/3, -1/3],[1/2],27*x)-1). - Mark van Hoeij, Nov 02 2009
a(n+1) = 6*(3*n+2)*(3*n+1)*a(n)/((2+n)*(2*n+3)). - Robert Israel, Nov 17 2014
a(n) ~ 3^(3*n + 1/2) / (4*sqrt(Pi)*n^(5/2)). - Vaclav Kotesovec, Mar 26 2016
E.g.f.: 2F2(1/3,2/3; 3/2,2; 27*x). - Ilya Gutkovskiy, Jan 25 2017

Extensions

Edited by N. J. A. Sloane, Dec 20 2008 at the suggestion of R. J. Mathar

A213978 Number of solid standard Young tableaux of shape [[n,n,n],[n]].

Original entry on oeis.org

1, 3, 91, 5471, 464836, 48767805, 5900575762, 791402291063, 114754560003596, 17688389169462060, 2864042102057254739, 482894371222455465001, 84225614036198359288620, 15119622005825185224290830, 2782232873996840900804273236, 523114052492282720617167786279, 100231256005025286627952024093564, 19528383010645472628217323778258916
Offset: 0

Views

Author

N. J. A. Sloane, Jul 07 2012

Keywords

Comments

Ekhad-Zeilberger give 121 terms.

Crossrefs

Column k=3 of A214722.

Programs

  • Maple
    b:= proc(x, y, z, u) option remember; `if`({x, y, z, u}={0}, 1,
         `if`(x>y and x>u, b(x-1, y, z, u), 0)+`if`(y>z, b(x, y-1, z, u), 0)+
         `if`(z>0, b(x, y, z-1, u), 0)+`if`(u>0, b(x, y, z, u-1), 0))
        end:
    a:= n-> b(n$4):
    seq(a(n), n=0..20);  # Alois P. Heinz, Jul 19 2012
  • Mathematica
    b[x_, y_, z_, u_] := b[x, y, z, u] = If[Union[{x, y, z, u}] == {0}, 1, If[x>y && x>u, b[x-1, y, z, u], 0] + If[y>z, b[x, y-1, z, u], 0] + If[z>0, b[x, y, z-1, u], 0] + If[u>0, b[x, y, z, u-1], 0]]; a[n_] := b[n, n, n, n]; Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Mar 11 2014, after Alois P. Heinz *)

Formula

Conjecture: Limit n->infinity a(n)^(1/n) = 256. - Vaclav Kotesovec, Jul 17 2014

A214631 Number A(n,k) of solid standard Young tableaux of shape [[(n)^(k+1)],[n]^k]; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 6, 16, 1, 1, 20, 936, 192, 1, 1, 70, 85800, 379366, 2816, 1, 1, 252, 9962680, 1825221320, 249664758, 46592, 1, 1, 924, 1340103744, 14336196893200, 89261675900020, 221005209058, 835584, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 26 2012

Keywords

Examples

			Square array A(n,k) begins:
  1,    1,         1,              1,                    1, ...
  1,    2,         6,             20,                   70, ...
  1,   16,       936,          85800,              9962680, ...
  1,  192,    379366,     1825221320,       14336196893200, ...
  1, 2816, 249664758, 89261675900020, 70351928759681296000, ...
		

Crossrefs

Columns k=0-2 give: A000012, A006335, A214638.
Rows n=0-1 give: A000012, A000984.

Programs

  • Maple
    b:= proc(l) option remember; local m; m:= nops(l);
          `if`({map(x-> x[], l)[]}={0}, 1, add(add(`if`(l[i][j]>
          `if`(i=m or nops(l[i+1])
          `if`(nops(l[i])=j, 0, l[i][j+1]), b(subsop(i=subsop(
           j=l[i][j]-1, l[i]), l)), 0), j=1..nops(l[i])), i=1..m))
        end:
    A:= (n, k)-> b([[n$(k+1)], [n]$k]):
    seq(seq(A(n, d-n), n=0..d), d=0..8);
  • Mathematica
    b[l_] := b[l] = With[{m = Length[l]}, If[Union[Flatten[l]] == {0}, 1, Sum[Sum[If[l[[i, j]] > If[i == m || Length[l[[i+1]] ] < j, 0, l[[i+1, j]] ] && l[[i, j]] > If[Length[l[[i]] ] == j, 0, l[[i, j+1]] ], b[ReplacePart[l, i -> ReplacePart[l[[i]], j -> l[[i, j]]-1]]], 0], {j, 1, Length[l[[i]] ]}], {i, 1, m}]]]; a[n_, k_] := b[{Array[n&, k+1], Sequence @@ Array[{n}&, k]}]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 8}] // Flatten (* Jean-François Alcover, Dec 18 2013, translated from Maple *)

A214824 Number of solid standard Young tableaux of shape [[(2)^n],[2]].

Original entry on oeis.org

2, 16, 91, 456, 2145, 9724, 43043, 187408, 806208, 3436720, 14545982, 61214960, 256411935, 1069854660, 4449173475, 18450500640, 76326664260, 315077780160, 1298203997610, 5340028714800, 21932944632690, 89963953083576, 368565304248846, 1508283816983776
Offset: 1

Views

Author

Alois P. Heinz, Jul 28 2012

Keywords

Comments

a(n) is odd if and only if n = 3 or n in { 2^k-3, 2^k-1 : k = 3,4,5, ... }.

Crossrefs

Row n=2 of A214722 and of A259101.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=1, 2,
          (4+(18+(22+4*n)*n)*n)*n*a(n-1)/(6+(-13+(1+(5+n)*n)*n)*n))
        end:
    seq(a(n), n=1..30);
  • Mathematica
    a[1] = 2; a[n_] := a[n] = (4 + (18 + (22 + 4*n)*n)*n)*n*a[n - 1]/(6 + (-13 + (1 + (5 + n)*n)*n)*n); Array[a, 30] (* Jean-François Alcover, Nov 08 2017, translated from Maple *)

Formula

a(n) = 2*(2*n+1)*(n^2+5*n+2)*n/((n-1)*(n+3)*(n^2+3*n-2))*a(n-1); a(1) = 2.

A215220 Number of solid standard Young tableaux of shape [[n,n,n,n],[n]].

Original entry on oeis.org

1, 4, 456, 143164, 75965484, 55824699632, 51274161733160, 55418842406649988, 67819708829687672202, 91539069926354814114556, 133752944758581353219955762, 208673064320580765981337783096, 343997162091593719562479905281938, 594344377404793356460064021706935470
Offset: 0

Views

Author

Alois P. Heinz, Aug 06 2012

Keywords

Crossrefs

Column k=4 of A214722.

Programs

  • Maple
    b:= proc(w, x, y, z, u) option remember;
         `if`({w, x, y, z, u}={0}, 1, `if`(w>x and w>u, b(w-1, x, y, z, u), 0)+
         `if`(x>y, b(w, x-1, y, z, u), 0)+ `if`(y>z, b(w, x, y-1, z, u), 0)+
         `if`(z>0, b(w, x, y, z-1, u), 0)+ `if`(u>0, b(w, x, y, z, u-1), 0))
        end:
    a:= n-> b(n$5):
    seq(a(n), n=0..20);
  • Mathematica
    b[w_, x_, y_, z_, u_] := b[w, x, y, z, u] =
      If[Union@{w, x, y, z, u} == {0}, 1,
      If[w > x && w > u, b[w - 1, x, y, z, u], 0] +
      If[x > y, b[w, x - 1, y, z, u], 0] +
      If[y > z, b[w, x, y - 1, z, u], 0] +
      If[z > 0, b[w, x, y, z - 1, u], 0] +
      If[u > 0, b[w, x, y, z, u - 1], 0]];
    a[n_] :=  b[n, n, n, n, n];
    Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Nov 08 2017, translated from Maple *)

A211505 Number of solid standard Young tableaux of shape [[(3)^n],[3]].

Original entry on oeis.org

5, 192, 5471, 143164, 3636776, 91442364, 2293620329, 57583680440, 1449149180310, 36577522323264, 926132803592304, 23521922685452320, 599176262762762880, 15305331537941936820, 391972832520910172865, 10062682947669846370800, 258904473727824391312650
Offset: 1

Views

Author

Alois P. Heinz, Aug 06 2012

Keywords

Comments

a(n) is odd if and only if n = 2^k-1, k in {1, 2, 3, ... }.

Crossrefs

Row n=3 of A214722.
Cf. A000225.

Programs

  • Maple
    a:=proc(n) option remember; `if`(n<3, [5, 192][n],
       ((-300307980720421134*n^6 -450257143569814251*n^5 +520721206232593545*n^4
        +237675576478617990*n^3 -244917832991741721*n^2 +20947752092648421*n
        +7263907687560150)*a(n-2) +(20284627624231332*n^6 +74969736339564876*n^5
        -90577816139486502*n^4 -578021108537112633*n^3 -713543105276625459*n^2
        -309855589348004634*n -29055630750240600)*a(n-1)) / (339337400732270*n^6
        +2086412513047793*n^5 -1761594949059583*n^4 -24340927184757907*n^3
        -25005499944921313*n^2 +25705682578023740*n +29939073413286900))
       end:
    seq(a(n), n=1..20);
  • Mathematica
    Table[(600 + 2874*n + 4709*n^2 + 3246*n^3 + 1019*n^4 + 144*n^5 + 8*n^6)*(2+3*n)! / (2*(3+2*n)*(5+2*n)*(n-1)!*(2+n)!*(5+n)!), {n, 1, 20}] (* Vaclav Kotesovec, Jul 16 2014 *)

Formula

a(n) = (600 + 2874*n + 4709*n^2 + 3246*n^3 + 1019*n^4 + 144*n^5 + 8*n^6)*(2+3*n)! / (2*(3+2*n)*(5+2*n)*(n-1)!*(2+n)!*(5+n)!). - Vaclav Kotesovec, Jul 16 2014

A258583 Number of solid standard Young tableaux of shape [[{n}^n],[n]].

Original entry on oeis.org

1, 1, 16, 5471, 75965484, 70692556053053, 6614511157454872712100, 87353366195666890516586545068535, 217757982462900115559339884671224174403391534, 132100470099008733697710444705793312015509514686031193798241, 24431421930145927713526351934816506384811205836191828228900485331569907542066
Offset: 0

Views

Author

Alois P. Heinz, Nov 06 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(l) option remember; local m; m:= nops(l);
          `if`({map(x-> x[], l)[]}={0}, 1, add(add(`if`(l[i][j]>
          `if`(i=m or nops(l[i+1])
          `if`(nops(l[i])=j, 0, l[i][j+1]), b(subsop(i=subsop(
           j=l[i][j]-1, l[i]), l)), 0), j=1..nops(l[i])), i=1..m))
        end:
    a:= n-> b([[n$n], [n]]):
    seq(a(n), n=0..8);
  • Mathematica
    b[l_] := b[l] = With[{m = Length[l]}, If[Union[Flatten[l]] == {0}, 1, Sum[Sum[ If[l[[i, j]] > If[i == m || Length[l[[i+1]]] If[Length[l[[i]]] == j, 0, l[[i, j+1]]], b[ReplacePart[l, i -> ReplacePart[ l[[i]], j -> l[[i, j]]-1]]], 0], {j, Length[l[[i]]]}], {i, m}]]];
    a[n_] := b[{Array[n&, n], {n}}];
    Table[a[n], {n, 0, 8}] (* Jean-François Alcover, Aug 25 2021, after Alois P. Heinz *)

Formula

a(n) = A214722(n,n).

A258586 Number of solid standard Young tableaux of shape [[{n}^(n+1)],[n]^n].

Original entry on oeis.org

1, 2, 936, 1825221320, 70351928759681296000, 160978956785364112335731878007698260, 51488321677815455036453939239317069333712945710369620220, 4648889159675386017282064494039528050991187044317172798976485350954735075040045120
Offset: 0

Views

Author

Alois P. Heinz, Nov 06 2015

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(l) option remember; local m; m:= nops(l);
          `if`({map(x-> x[], l)[]}={0}, 1, add(add(`if`(l[i][j]>
          `if`(i=m or nops(l[i+1])
          `if`(nops(l[i])=j, 0, l[i][j+1]), b(subsop(i=subsop(
           j=l[i][j]-1, l[i]), l)), 0), j=1..nops(l[i])), i=1..m))
        end:
    a:= n-> b([[n$(n+1)], [n]$n]):
    seq(a(n), n=0..5);
Showing 1-8 of 8 results.