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.

A362167 a(n) = the hypergraph Catalan number C_2(n).

Original entry on oeis.org

1, 1, 6, 57, 678, 9270, 139968, 2285073, 39871926, 739129374, 14521778820, 302421450474, 6687874784484, 157491909678168, 3961138908376692, 106663881061254465, 3078671632202791782, 95213375569840078422, 3149291101933230285924, 111073721303120881912686
Offset: 0

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Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 2.
Let T(n) be the set of unlabeled trees on n vertices (see A000055). Let T be a tree in T(n+1), and let v be a vertex of T. Then an a(m,T)-tour beginning at v is a walk that begins and ends at v and traverses each edge of T exactly 2*m times. We denote by a(m,T)(v) the number of a(m,T)-tours beginning at v.
The hypergraph Catalan numbers C_m(n) are defined by C_m(n) = Sum_{trees T in T(n+1)} Sum_{vertices v in T} a(m,T)(v)/|Aut(T)|, where Aut(T) denotes the automorphism group of the tree T.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Programs

Formula

a(n) ~ e^(3/2) * 2^(n+1) * n!/sqrt(Pi*n) (conjectural).

Extensions

a(11) onwards from Andrew Howroyd, Jan 31 2024

A362172 a(n) = the hypergraph Catalan number C_7(n).

Original entry on oeis.org

1, 1, 3432, 141858288, 40309820014464, 53321581727982247680, 238681094467043912358445056, 2924960829706245011243295851200512, 84750120431280677998861681616641721991168, 5208807724759446156144077076658272647436908396544
Offset: 0

Views

Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. See Gunnells. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 7.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Formula

a(n) ~ sqrt(7)/4 * (7^6/6!)^n * n!^6/(Pi*n)^3 (conjectural).

Extensions

a(7) onwards from Andrew Howroyd, Feb 01 2024

A362168 a(n) = the hypergraph Catalan number C_3(n).

Original entry on oeis.org

1, 1, 20, 860, 57200, 5344800, 682612800, 118180104000, 27396820448000, 8312583863720000, 3209035788149600000, 1534218535286625760000, 888028389273314675200000, 611029957551257895664000000, 492466785518772137553984000000, 459270692175324078697443840000000
Offset: 0

Views

Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. See Gunnells. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 3.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Programs

Formula

a(n) ~ sqrt(3) * (9/2)^n * n!^2/(Pi*n) (conjectural).

Extensions

a(9) onwards from Andrew Howroyd, Feb 01 2024

A362169 a(n) = the hypergraph Catalan number C_4(n).

Original entry on oeis.org

1, 1, 70, 15225, 7043750, 6327749750, 10411817136000, 29034031694460625, 126890003304310093750, 816448082514611102718750, 7379204202189710013311562500, 90369225128606332243844280406250, 1457163640851863433667228849319062500, 30217741884769257764596041337071409375000
Offset: 0

Views

Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. See Gunnells. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 4.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Programs

Formula

a(n) ~ sqrt(2) * (32/3)^n * n!^3/(Pi*n)^(3/2) (conjectural).

Extensions

a(8) onwards from Andrew Howroyd, Feb 01 2024

A362170 a(n) = the hypergraph Catalan number C_5(n).

Original entry on oeis.org

1, 1, 252, 299880, 1112865264, 11126161436292, 255654847841227632, 11676346013544951854304, 953196481551725431240711680, 128864126679853773803689954958112, 27235509875891350493949247236459319296, 8599544533810439129313490410035564948257536
Offset: 0

Views

Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. See Gunnells. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 5.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Formula

a(n) ~ sqrt(5)/2 * (5^4/24)^n * n!^4/(Pi*n)^2 (conjectural).

Extensions

a(7) onwards from Andrew Howroyd, Feb 01 2024

A362171 a(n) = the hypergraph Catalan number C_6(n).

Original entry on oeis.org

1, 1, 924, 6358044, 203356067376, 23345633108619360, 7484535614458774428480, 5583028528736289502562408256, 8547031978688473343843434600852224, 24503310825110075324451531207978424853568, 122607946140627185219752569884701085604290069760
Offset: 0

Views

Author

Peter Bala, Apr 10 2023

Keywords

Comments

Let m >= 1. The sequence of hypergraph Catalan numbers {C_m(n): n >= 0} is defined in terms of counting walks on trees, weighted by the orders of their automorphism groups. See Gunnells. When m = 1 we get the sequence of Catalan numbers A000108. The present sequence is the case m = 6.
Gunnells gives several combinatorial interpretations of the hypergraph Catalan numbers, a method to compute their generating functions to arbitrary precision and some conjectural asymptotics.

Crossrefs

Formula

a(n) ~ sqrt(3)/2 * (6^5/5!)^n * n!^5/(Pi*n)^(5/2) (conjectural)

Extensions

a(6) onwards from Andrew Howroyd, Feb 01 2024
Showing 1-6 of 6 results.