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.

A368025 Array read by ascending antidiagonals: A(n,k) is the determinant 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, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 5, 1, 1, 1, 4, 14, 14, 1, 1, 1, 5, 30, 84, 42, 1, 1, 1, 6, 55, 330, 594, 132, 1, 1, 1, 7, 91, 1001, 4719, 4719, 429, 1, 1, 1, 8, 140, 2548, 26026, 81796, 40898, 1430, 1, 1, 1, 9, 204, 5712, 111384, 884884, 1643356, 379236, 4862, 1
Offset: 0

Views

Author

Stefano Spezia, Dec 08 2023

Keywords

Comments

This array is a variant of the triangles A078920 and A123352 extended to the trivial cases (here for k=0).

Examples

			The array begins:
  1, 1, 1,   1,    1,      1,        1, ...
  1, 1, 2,   5,   14,     42,      132, ...
  1, 1, 3,  14,   84,    594,     4719, ...
  1, 1, 4,  30,  330,   4719,    81796, ...
  1, 1, 5,  55, 1001,  26026,   884884, ...
  1, 1, 6,  91, 2548, 111384,  6852768, ...
  1, 1, 7, 140, 5712, 395352, 41314284, ...
  ...
		

Crossrefs

Cf. A000108 (n=1), A005700 (n=2), A006149 (n=3), A006150 (n=4), A006151 (n=5).
Cf. A000012 (k=0 or k=1 or n=0), A000330, A078920, A091962, A123352, A335857 (k=6).
Cf. A355400, A368026 (permanent), A378112.
Antidiagonal sums give A355503.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(k=0, 1, 2^n*mul(
          (2*(k-i)+2*n-3)/(k+2*n-1-i), i=0..n-1)*A(n, k-1))
        end:
    seq(seq(A(d-k, k), k=0..d), d=0..10);  # Alois P. Heinz, Dec 20 2023
  • Mathematica
    A[n_,k_]:=If[n==0,1,Det[Table[CatalanNumber[i+j+k],{i,0,n-1},{j,0,n-1}]]]; Table[A[n-k,k],{n,0,11},{k,0,n}]//Flatten

Formula

For an explicit formula of A(n,k), see equation (5) in Feng, 2020.
A(n,2) = n + 1.
A(n,3) = A000330(n+1).
A(n,4) = A006858(n+1).
A(n,5) = A091962(n+1).
Diagonal: A(n,n) = A123352(2*n-1,n-1) = A355400(n).

A368021 a(n) 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+3) with i,j = 0, ..., n-1.

Original entry on oeis.org

1, 5, 406, 490614, 8755482505, 2318987094804471, 9179129956137993425772, 546580120389987275414413168012, 492460174883711250780962744103403975159, 6747075036368337341936435881321217868978170152215, 1411689504898999110533224343869931312130954127737962059963934
Offset: 0

Views

Author

Stefano Spezia, Dec 08 2023

Keywords

Examples

			a(4) = 8755482505:
    5,  14,  42,   132;
   14,  42, 132,   429;
   42, 132, 429,  1430;
  132, 429, 1430, 4862.
		

Crossrefs

Programs

  • Mathematica
    Join[{1},Table[Permanent[Table[CatalanNumber[i+j+3],{i,0,n-1},{j,0,n-1}]],{n,10}]]
  • PARI
    C(n) = binomial(2*n, n)/(n+1); \\ A000108
    a(n) = matpermanent(matrix(n, n, i, j, C(i+j+1))); \\ Michel Marcus, Dec 11 2023

Formula

Det(M(n)) = A000330(n+1) (see Mays and Wojciechowski, 2000).

A358597 Number of n-tuples (p_1, p_2, ..., p_n) of Dyck paths of semilength n+1, such that each p_i is never below p_{i-1}.

Original entry on oeis.org

1, 2, 14, 330, 26026, 6852768, 6018114036, 17618122000050, 171879976152056250, 5586863607659640852000, 604960371578930672694585600, 218201797452928091289631307694720, 262138086905421645845923269465748817136, 1048861003938217198101763464819634006647101600
Offset: 0

Views

Author

Alois P. Heinz, Feb 24 2023

Keywords

Examples

			a(0) = 1:  ().
                     /\
a(1) = 2:  (/\/\), (/  \).
		

Crossrefs

Programs

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

Formula

a(n) = A078920(2n,n) = A123352(2n,n).
a(n) ~ exp(1/24) * 2^(2/3 + 5*n + 8*n^2) / (sqrt(A) * n^(1/24) * 3^(9*n^2/2 + 3*n + 5/12)), where A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Aug 26 2023

A378113 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} and the upper path p_n only touches the x-axis at its endpoints.

Original entry on oeis.org

1, 1, 2, 23, 880, 105554, 40446551, 50637232553, 209584899607676, 2881189188022646406, 131778113962930341491415, 20065327661524165382215337625, 10173706896856510992170168595911888, 17178054578218938036671513200907244799852, 96590987238453485101729361602126273065518820938
Offset: 0

Views

Author

Alois P. Heinz, Nov 16 2024

Keywords

Examples

			a(2) = 2:
          /\       /\   /\
   (/\/\,/  \)   (/  \,/  \) .
The a(3) = 23 3-tuples can be encoded as 114, 115, 124, 125, 134, 135, 144, 145, 155, 224, 225, 244, 245, 255, 334, 335, 344, 345, 355, 444, 445, 455, 555, where the digits represent the following Dyck paths:
  1        2        3        4        5 /\
            /\         /\     /\/\     /  \
  /\/\/\   /  \/\   /\/  \   /    \   /    \ .
		

Crossrefs

Main diagonal of A378112.

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, 2^k*mul(
          (2*(n-i)+2*k-3)/(n+2*k-1-i), i=0..k-1)*b(n-1, k))
        end:
    A:= proc(n, k) option remember;
          b(n, k)-add(A(n-i, k)*b(i, k), i=1..n-1)
        end:
    a:= n-> A(n$2):
    seq(a(n), n=0..15);

Formula

a(n) = A378112(n,n).

A355503 Total number of m-tuples (p_1, p_2, ..., p_m) of Dyck paths of semilength n-m, such that each p_i is never below p_{i-1} for m=0..n.

Original entry on oeis.org

1, 2, 3, 5, 11, 35, 164, 1120, 10969, 152849, 3029650, 85227078, 3400752392, 192644205130, 15470939367651, 1761760468965521, 284641456742538865, 65175288287611738435, 21159611204475209730138, 9743708333490185603430830, 6357930817596444858142966826
Offset: 0

Views

Author

Alois P. Heinz, Jul 04 2022

Keywords

Examples

			a(3) = 5: ( ), (/\/\), (//\\), (/\, /\, /\), (<>, <>, <>, <>).
		

Crossrefs

Antidiagonal sums of A368025.

Programs

  • Maple
    a:= n-> add(mul(mul((i+j+2*(n-m))/(i+j), j=i..m-1), i=1..m-1), m=0..n):
    seq(a(n), n=0..23);
  • Mathematica
    Table[Sum[Product[Product[(i+j+2*(n-m))/(i+j), {j,i,m-1}], {i,1,m-1}], {m,0,n}], {n,0,20}] (* Vaclav Kotesovec, Aug 27 2023 *)
    Table[Sum[BarnesG[1 + m] * Sqrt[BarnesG[1 + 2*n] * BarnesG[2 - 2*m + 2*n] * Gamma[1 + 2*m] * Gamma[1 + n] / (BarnesG[1 + 2*m] * Gamma[1 + m] * Gamma[1 + 2*n] * Gamma[1 - m + n])] / BarnesG[1 - m + 2*n], {m, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 27 2023 *)

Formula

a(n) = Sum_{m=0..n} Product_{i=1..m-1, j=i..m-1} (i+j+2*(n-m))/(i+j).
a(n) = 1 + Sum_{k=0..n-1} A078920(n-1,k).
a(n) = 1 + Sum_{k=0..n-1} A123352(n-1,k).
a(n) = Sum_{k=0..n} A368025(n-k, k).
From Vaclav Kotesovec, Aug 27 2023: (Start)
a(n) ~ c * exp(1/24) * 3^(n^2 - n/2) / (sqrt(A) * n^(1/24) * 2^((4*n^2-n-1)/3)), where A = A074962 is the Glaisher-Kinkelin constant and
c = Sum_{k,-oo,oo} 2^((k + mod(n,3)/3)/2 - 3*(k + mod(n,3)/3)^2/2).
Numerically, c = 1.78933741155287907159762028... if mod(n,3)=0 or mod(n,3)=1 and c = 1.78893263307672974352375161... if mod(n,3)=2. (End)

A368298 a(n) 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+n) with i,j = 0, ..., n-1.

Original entry on oeis.org

1, 1, 53, 490614, 930744290905, 386735380538157813864, 36494318768452684668237864399892, 800075179375382235705309991148469060609055210, 4138855242465150993428071754285859188133806122546895149328625, 5109461743591866972924602083859433690113667142460933537037028649653229023827000
Offset: 0

Views

Author

Stefano Spezia, Dec 20 2023

Keywords

Examples

			a(3) = 490614:
   5,  14,  42;
  14,  42, 132;
  42, 132, 429.
		

Crossrefs

Diagonal of A368025.

Programs

  • Maple
    with(LinearAlgebra):
    C:= proc(n) option remember; binomial(2*n, n)/(n+1) end:
    a:= n-> `if`(n=0, 1, Permanent(Matrix(n, (i, j)-> C(i+j+n-2)))):
    seq(a(n), n=0..10);  # Alois P. Heinz, Dec 20 2023
  • Mathematica
    a[n_]:=If[n==0, 1, Permanent[Table[CatalanNumber[i+j+n], {i, 0, n-1}, {j, 0, n-1}]]]; Array[a,10,0]
Showing 1-6 of 6 results.