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.

A214775 Number T(n,k) of solid standard Young tableaux of shape [[n,k],[n-k]]; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 2, 6, 2, 5, 25, 25, 5, 14, 98, 174, 98, 14, 42, 378, 962, 962, 378, 42, 132, 1452, 4804, 7020, 4804, 1452, 132, 429, 5577, 22689, 43573, 43573, 22689, 5577, 429, 1430, 21450, 103510, 245962, 325590, 245962, 103510, 21450, 1430
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2012

Keywords

Comments

T(n,k) is odd if and only if n = 2^i-1 for i in {0, 1, 2, ... } = A001477.

Examples

			Triangle T(n,k) begins:
    1;
    1,    1;
    2,    6,    2;
    5,   25,   25,    5;
   14,   98,  174,   98,   14;
   42,  378,  962,  962,  378,   42;
  132, 1452, 4804, 7020, 4804, 1452, 132;
  ...
		

Crossrefs

Columns 0-5 give: A000108, A214955, A215298, A215299, A215300, A215301.
Row sums give: A215002.
Central row elements give: A214801.

Programs

  • Maple
    b:= proc(x, y, z) option remember; `if`(z>y, b(x, z, y),
          `if`({x, y, z}={0}, 1, `if`(x>y and x>z, b(x-1, y, z), 0)+
          `if`(y>0, b(x, y-1, z), 0)+ `if`(z>0, b(x, y, z-1), 0)))
        end:
    T:= (n, k)-> b(n, k, n-k):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[x_, y_, z_] := b[x, y, z] = If[z>y, b[x, z, y], If[Union[{x, y, z}] == {0}, 1, If[x>y && x>z, b[x-1, y, z], 0] + If[y>0, b[x, y-1, z], 0] + If[z>0, b[x, y, z-1], 0]]]; T[n_, k_] := b[n, k, n-k]; Table[T[n, k] , {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jan 15 2014, translated from Maple *)
  • Sage
    @CachedFunction
    def B(x, y, z) :
        if z > y : return B(x, z, y)
        if x==y and y==z and z==0 : return 1
        a = B(x-1, y, z) if x>y and x>z else 0
        b = B(x, y-1, z) if y>0 else 0
        c = B(x, y, z-1) if z>0 else 0
        return a + b + c
    T = lambda n, k: B(n, k, n-k)
    [[T(n, k) for k in (0..n)] for n in (0..10)]
    # After Maple code of Alois P. Heinz. Peter Luschny, Jul 30 2012

A214955 Number of solid standard Young tableaux of shape [[n,n-1],[1]].

Original entry on oeis.org

1, 6, 25, 98, 378, 1452, 5577, 21450, 82654, 319124, 1234506, 4784276, 18572500, 72209880, 281150505, 1096087770, 4278278070, 16717354500, 65388738030, 256000696380, 1003116947820, 3933750236520, 15437682614250, 60625494924228, 238235373671148, 936735006679752
Offset: 1

Views

Author

Alois P. Heinz, Jul 30 2012

Keywords

Comments

a(n) is odd if and only if n = 2^i-1 for i in {1, 2, 3, ...} = A000027.
Form an array with m(1,n) = n*(n+1)/2, m(n,1) = n*(n-1)+1, and m(i,j) = m(i,j-1) + m(i-1,j); A000217 in the top row, A002061 in the first column, A086514 in the second column. Then on the diagonal m(n,n) = a(n). - J. M. Bergot, May 02 2013

Crossrefs

Column k=1 of A214775.

Programs

  • Maple
    a:= proc(n) option remember;
          `if`(n<2, n, 2*(2*n-1)^2*a(n-1)/((n+1)*(2*n-3)))
        end:
    seq(a(n), n=1..30);
  • Mathematica
    a[n_]:= a[n] = If[n<2, n, 2*(2*n-1)^2*a[n-1]/((n+1)*(2*n-3))]; Array[a, 30] (* Jean-François Alcover, Aug 14 2017, translated from Maple *)
  • PARI
    a(n) = (2*n-1) * binomial(2*n,n)/(n+1); \\ Michel Marcus, Mar 06 2022

Formula

a(n) = 2*(2*n-1)^2/((n+1)*(2*n-3)) * a(n-1) for n>1; a(1) = 1.
a(n) = (2*n-1) * C(2*n,n)/(n+1) = A060747(n) * A000108(n).
a(n) = [x^n] x*(1 + 2*x)/(1 - x)^(n+2). - Ilya Gutkovskiy, Oct 12 2017
Sum_{n>=1} 1/a(n) = 1/6 + G + 13*Pi/(36*sqrt(3)) - Pi*log(2+sqrt(3))/8, where G is Catalan's constant (A006752). - Amiram Eldar, Mar 06 2022
From Stefano Spezia, Mar 29 2023: (Start)
O.g.f.: 1 + (3 - 3*sqrt(1 - 4*x) - 8*x)/(2*x*sqrt(1 - 4*x)).
E.g.f.: 1 + exp(2*x)*(3*I_1(2*x) - I_0(2*x)), where I_n(x) is the modified Bessel function of the first kind.
a(n) ~ 2^(1+2*n)/sqrt(n*Pi). (End)

A215298 Number of solid standard Young tableaux of shape [[n,n-2],[2]].

Original entry on oeis.org

2, 25, 174, 962, 4804, 22689, 103510, 461318, 2021916, 8752042, 37520972, 159633060, 674969224, 2839400945, 11893509990, 49637986590, 206519808300, 856904298030, 3547095101220, 14652264350940, 60412895258040, 248675669866650, 1022088942267900, 4195255959533052
Offset: 2

Views

Author

Alois P. Heinz, Aug 07 2012

Keywords

Crossrefs

Column k=2 of A214775.
Cf. A215002.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=2, 2,
          2*(4*n^5 -26*n^4 +60*n^3 -58*n^2 +22*n -5)*a(n-1)/
            (2*n^5 -14*n^4 +30*n^3 -10*n^2 -31*n +25))
        end:
    seq(a(n), n=2..30);
  • Mathematica
    Table[12*(1 - 4*n + 10*n^2 - 8*n^3 + 2*n^4) * (2*n-4)! / ((n-2)! * (n+1)!), {n, 2, 20}] (* Vaclav Kotesovec, Sep 02 2014 *)

Formula

See Maple program.
a(n) ~ 3 * 2^(2*n-1) * sqrt(n) / sqrt(Pi). - Vaclav Kotesovec, Sep 02 2014
a(n) = 12*(1 - 4*n + 10*n^2 - 8*n^3 + 2*n^4) * (2*n-4)! / ((n-2)! * (n+1)!). - Vaclav Kotesovec, Sep 02 2014

A215299 Number of solid standard Young tableaux of shape [[n,n-3],[3]].

Original entry on oeis.org

5, 98, 962, 7020, 43573, 245962, 1305238, 6633172, 32649890, 156817044, 738717796, 3425580376, 15679951989, 70992594650, 318450985230, 1417072222020, 6261985407990, 27502477286460, 120137081521500, 522256720264680, 2260525598620770, 9746264904755652
Offset: 3

Views

Author

Alois P. Heinz, Aug 07 2012

Keywords

Crossrefs

Column k=3 of A214775.
Cf. A215002.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<5, [0$2, 5, 98][n],
          2*(32*n^7 -400*n^6 +1976*n^5 -4900*n^4 +6452*n^3 -4420*n^2
          +1350*n-315)*a(n-1) / (16*n^7 -224*n^6 +1204*n^5 -3008*n^4
          +2980*n^3 +1072*n^2 -4155*n +2205))
        end:
    seq(a(n), n=3..30);
  • Mathematica
    Flatten[{5, Table[(8*(45 - 180*n + 580*n^2 - 756*n^3 + 484*n^4 - 144*n^5 + 16*n^6) * (2*n-6)!) / (3*(n-3)!*(n+1)!), {n, 4, 20}]}] (* Vaclav Kotesovec, Sep 02 2014 *)

Formula

See Maple program.
For n > 3, a(n) = (8*(45 - 180*n + 580*n^2 - 756*n^3 + 484*n^4 - 144*n^5 + 16*n^6) * (2*n-6)!) / (3 * (n-3)! * (n+1)!). - Vaclav Kotesovec, Sep 02 2014

A215300 Number of solid standard Young tableaux of shape [[n,n-4],[4]].

Original entry on oeis.org

14, 378, 4804, 43573, 325590, 2149454, 13054108, 74688594, 408634828, 2159302420, 11097147528, 55747502501, 274790652518, 1332928973766, 6377276361900, 30149660760870, 141057202034340, 653892592144620, 3006490865152440, 13722387184879650, 62220533305358076
Offset: 4

Views

Author

Alois P. Heinz, Aug 07 2012

Keywords

Crossrefs

Column k=4 of A214775.
Cf. A215002.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<6, [0$3, 14, 378, 4804][n],
          ((-460961029024*n^4 +54902186125572*n^3 -347074341314956*n^2
           +421934757637074*n +6838164520124) *a(n-1) +(104238656896016*n^4
           -2317913124589048*n^3 +16535317231755832*n^2 -44274446438628908*n
           +29901662719961532)*a(n-2) +(-391233321452352*n^4
           +7447800734464704*n^3 -48294258553516272*n^2 +122447135865649584*n
           -105955729051546080)*a(n-3)) / (286655151052*n^4 -1210962058579*n^3
           +4322649356693*n^2 -24951473774234*n -30771740340558))
        end:
    seq(a(n), n=4..30);
  • Mathematica
    Flatten[{14,Table[(2*(n-5))!/(3*(n-5)!*(n+1)!)*(160*(-567+2394*n-8862*n^2+15592*n^3-15484*n^4+9152*n^5-3292*n^6+704*n^7-82*n^8+4*n^9)),{n,5,20}]}] (* Vaclav Kotesovec, Sep 02 2014 *)

Formula

See Maple program.
For n > 4, a(n) = (2*(n-5))!/(3*(n-5)!*(n+1)!)*(160*(-567 + 2394*n - 8862*n^2 + 15592*n^3 - 15484*n^4 + 9152*n^5 - 3292*n^6 + 704*n^7 - 82*n^8 + 4*n^9)). - Vaclav Kotesovec, Sep 02 2014

A215301 Number of solid standard Young tableaux of shape [[n,n-5],[5]].

Original entry on oeis.org

42, 1452, 22689, 245962, 2149454, 16290708, 111709178, 711996820, 4292788212, 24777783256, 138077129921, 747501664986, 3949741123174, 20444004524804, 103955714523390, 520494659493180, 2570907398453580, 12546842041060200, 60579487688891610, 289692893191143876
Offset: 5

Views

Author

Alois P. Heinz, Aug 07 2012

Keywords

Crossrefs

Column k=5 of A214775.
Cf. A215002.

Programs

  • Maple
    a:=proc(n) option remember; `if`(n<7, [0$4, 42, 1452, 22689][n],
       ((-940984202308081409937789248*n^7+36378423601372783158274124928*n^6
        -540987251973268278464961515672*n^5+4140452478540141056223108638628*n^4
        -17643038551017281385645661643624*n^3+40489345935054116443261823323140*n^2
        -39934974057986427003556989745680*n-247683783218781902433156798480)*a(n-1)
        +(5038765510419498883689330496*n^7-154613008671019208064714735488*n^6
        +1939670093038831522623368803072*n^5-12888788321486668402366527701360*n^4
    +48941495657518683977159471709724*n^3-105016281014420890409086708155812*n^2
        +113403222542936117699329884355248*n-47046838608769352958257951122560)
        *a(n-2))/(79676793824198327746135844*n^7-1949805875384464242394656236*n^6
        +20900166698905174940775960603*n^5-125515785015357799830976856812*n^4
        +431332553464051479008795376439*n^3-723271251684163430971195319466*n^2
        +59211568171613916060478086240*n+1362260807703300463382362391640))
       end:
    seq(a(n), n=5..30);
  • Mathematica
    Flatten[{42, 1452, Table[(2*(n-6))! / (5 * (n-6)! * (n+1)!) * 64 * (-51975 + 217350*n - 873908*n^2 + 1738396*n^3 - 2038350*n^4 + 1500940*n^5 - 724004*n^6 + 231788*n^7 - 48750*n^8 + 6460*n^9 - 488*n^10 + 16*n^11), {n, 7, 20}]}]

Formula

See Maple program.
For n > 6, a(n) = (2*(n-6))! / (5 * (n-6)! * (n+1)!) * 64 * (-51975 + 217350*n - 873908*n^2 + 1738396*n^3 - 2038350*n^4 + 1500940*n^5 - 724004*n^6 + 231788*n^7 - 48750*n^8 + 6460*n^9 - 488*n^10 + 16*n^11). - Vaclav Kotesovec, Sep 02 2014
Showing 1-6 of 6 results.