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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A368026 Array read by ascending antidiagonals: A(n, k) is the permanent of the n-th order Hankel matrix of Catalan numbers M(n) whose generic element is given by M(i,j) = A000108(i+j+k) with i,j = 0, ..., n-1.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 95, 9, 2, 1, 38057, 979, 53, 5, 1, 207372681, 1417675, 19148, 406, 14, 1, 15977248385955, 28665184527, 97432285, 490614, 3612, 42, 1, 17828166968924572623, 8325587326635565, 7146659536022, 8755482505, 14798454, 35442, 132, 1, 292842668371666277607183121, 35389363346700690999467, 7683122105385590481, 2318987094804471, 930744290905, 499114473, 372801, 429, 1
Offset: 0

Views

Author

Stefano Spezia, Dec 08 2023

Keywords

Examples

			The array begins:
      1,       1,        1,          1,            1, ...
      1,       1,        2,          5,           14, ...
      3,       9,       53,        406,         3612, ...
     95,     979,    19148,     490614,     14798454, ...
  38057, 1417675, 97432285, 8755482505, 930744290905, ...
  ...
		

Crossrefs

Cf. A000012 (n=0), A000108 (n=1).
Cf. A368012 (k=0), A368019 (k=1), A278843 (k=2), A368021 (k=3), A368022 (k=4), A368023 (k=5), A368024 (k=6).
Cf. A368025 (determinant), A368298 (diagonal).

Programs

  • Maple
    with(LinearAlgebra):
    C:= proc(n) option remember; binomial(2*n, n)/(n+1) end:
    A:= (n, k)-> `if`(n=0, 1, Permanent(Matrix(n, (i, j)-> C(i+j+k-2)))):
    seq(seq(A(d-k, k), k=0..d), d=0..8);  # Alois P. Heinz, Dec 20 2023
  • Mathematica
    A[n_,k_]:=If[n==0,1,Permanent[Table[CatalanNumber[i+j+k],{i,0,n-1},{j,0,n-1}]]]; Table[A[n-k,k],{n,0,8},{k,0,n}]//Flatten

A355400 Number of n-tuples (p_1, p_2, ..., p_n) of Dyck paths of semilength n, such that each p_i is never below p_{i-1}.

Original entry on oeis.org

1, 1, 3, 30, 1001, 111384, 41314284, 51067020290, 210309203300625, 2885318087540733000, 131857099297936066411200, 20070377346929658409924542720, 10174783866874800701945612292557712, 17178820188393063395267380511228827387600, 96592800670609299321035523895170598736583965100
Offset: 0

Views

Author

Alois P. Heinz, Jun 30 2022

Keywords

Comments

Determinant of the n X n Hankel matrix whose i-th antidiagonal is filled with the n+i-th Catalan number for i = 0..2*n-2.
[ 5, 14, 42]
a(3) = det( [14, 42, 132] ) = 30.
[42, 132, 429]

Examples

			a(0) = 1:  ( ).
a(1) = 1:  (/\).
a(2) = 3:                        /\      /\    /\
           (/\/\, /\/\), (/\/\, /  \), (/  \, /  \).
G.f. = 1 + x + 3*x^2 + 30*x^3 + 1001*x^4 + 111384*x^5 + 41314284*x^6 + ... - _Michael Somos_, Jun 27 2023
		

Crossrefs

Programs

  • Maple
    a:= n-> mul(mul((i+j+2*n)/(i+j), j=i..n-1), i=1..n-1):
    seq(a(n), n=0..14);
  • Mathematica
    Join[{1}, Table[Sqrt[2*BarnesG[4*n]] * BarnesG[n] * Gamma[2*n]^(3/2) / BarnesG[3*n + 1], {n, 1, 12}]] (* Vaclav Kotesovec, Aug 26 2023 *)
  • PARI
    a(n) = prod(i=1, n-1, prod(j=i, n-1, (i+j+2*n)/(i+j))); \\ Michel Marcus, Jul 05 2022

Formula

a(n) = Product_{i=1..n-1, j=i..n-1} (i+j+2*n)/(i+j).
a(n) mod 2 = 1 <=> n in { A131577 }.
a(n) ~ exp(1/24) * 2^(1/6 - n + 8*n^2) / (sqrt(A) * n^(1/24) * 3^(9*n^2/2 - 1/12)), where A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Aug 26 2023
Showing 1-2 of 2 results.