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.

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A259711 Numbers that can be written as a product of Catalan numbers.

Original entry on oeis.org

1, 2, 4, 5, 8, 10, 14, 16, 20, 25, 28, 32, 40, 42, 50, 56, 64, 70, 80, 84, 100, 112, 125, 128, 132, 140, 160, 168, 196, 200, 210, 224, 250, 256, 264, 280, 320, 336, 350, 392, 400, 420, 429, 448, 500, 512, 528, 560, 588, 625, 640, 660, 672, 700, 784, 800, 840
Offset: 1

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Author

Ilya Gutkovskiy, Apr 14 2020

Keywords

Examples

			70 = 5*14 = C(3)*C(4). - _David A. Corneth_, Mar 26 2021
		

Crossrefs

A203195 (n-1)-st elementary symmetric function of the first n Catalan numbers (A000108).

Original entry on oeis.org

1, 2, 5, 27, 388, 16436, 2175432, 934036488, 1336005150480, 6496133192508960, 109111368146935714560, 6414259771390908431554560, 1334245289372299128934618629120, 991211300949703256415518451506380800
Offset: 1

Views

Author

Clark Kimberling, Dec 30 2011

Keywords

Crossrefs

Cf. A000108, A003046 (n-th elem. symm. func.), A014137 (1st elm. symm. func.).

Programs

  • Mathematica
    f[k_] := (1/k) Binomial[2 k - 2, k - 1];
    t[n_] := Table[f[k], {k, 1, n}]
    a[n_] := SymmetricPolynomial[n - 1, t[n]]
    Table[a[n], {n, 1, 14}]  (* A203195 *)

A248330 The product of the first n Catalan numbers and the number of standard Young tableaux of shape(1,2,...,n).

Original entry on oeis.org

1, 1, 4, 160, 107520, 1722040320, 854352419880960, 16185399027773630054400, 13931397052191274338996977664000, 632089112919018408339999461491467091968000, 1721041721929360607907210006858724622834371563356160000
Offset: 0

Views

Author

Alejandro H. Morales, Oct 04 2014

Keywords

Comments

The volume of a certain polytope (the Tesler polytope) whose lattice points are Tesler matrices (A008608), and with (n+1)! integral vertices (permutation Tesler matrices).
This is also the iterated constant term of the rational function (x1+x2+...+xn+x(n+1))^binomial(n+1,2)*product_{1<=i

Crossrefs

Programs

  • Maple
    A248330 := proc(n) local i; mul(binomial(2*k, k)/(1+k), k=0..n)*binomial(n+1, 2)!/ mul( (2*i+1)^(n-i), i=0..n-1 ); end;

Formula

a(n) = A005118(n+1) * A003046(n).
a(n) = A005118(n+1) * Product_{k=0..n} A000108(k).

A324565 a(n) = Product_{i=0..n, j=0..n} (C(i)+C(j)), where C(k) = Catalan(k) = A000108(k).

Original entry on oeis.org

2, 16, 5184, 3292047360, 431257150704844800000, 1660988174371634812975670031600844800000, 29842277901990912803108442836098281105491323166448779304684748800000
Offset: 0

Author

Vaclav Kotesovec, Mar 07 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[CatalanNumber[i] + CatalanNumber[j], {i, 0, n}, {j, 0, n}], {n, 0, 7}]

Formula

a(n) ~ c * d^n * 2^(4*n^3/3 + 3*n^2) * exp(3*n^2/4) / (Pi^(n^2/2) * n^(3*n^2/2 + 3*n - alfa)), where
d = 1.755243767008515125359629831741161625491476427596217377285488419728083846...
alfa = 0.033913207252709141540468528132950860454628430850651543265936300855299...
c = 1.31959917222402005903928675604752142566298009509...

A247859 The product of the first n Catalan numbers and 2^(n^2).

Original entry on oeis.org

1, 2, 32, 5120, 9175040, 197300060160, 53337309063413760, 187446932178571288903680, 8783433335287216312557974323200, 5597436690584888372318289416604667084800, 49290698636690081763273206158480893991348233830400, 6076713947745931800683801366458443411856602743866957548748800
Offset: 0

Author

Alejandro H. Morales, Sep 25 2014

Keywords

Comments

The volume of a certain polytope (the type D_(n+2) Chan-Robbins-Yuen polytope). This was conjectured by Meszaros-Morales and proved independently by Zeilberger and Kim, both using a variant of the Morris constant term identity (just as for the original Chan-Robbins-Yuen polytope).

Crossrefs

Cf. A000108 (Catalan numbers).
Cf. A003046 (Product of first n Catalan numbers).

Programs

  • Maple
    seq(2^(n^2)*mul(binomial(2*k, k)/(1+k), k=0..n), n=0..13);
  • Mathematica
    a[n_] := 2^(n^2)*Product[ CatalanNumber[k], {k, 0, n}]; Table[a[n], {n, 0, 13}]

Formula

a(n) = 2^(n^2) * A003046(n).
a(n) = 2^(n^2) * prod(k=0..n) A000108(k).
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