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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A369288 Array read by antidiagonals: A(n,k) = the hypergraph Catalan number C_k(n), n >= 0, k >= 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 6, 5, 1, 1, 20, 57, 14, 1, 1, 70, 860, 678, 42, 1, 1, 252, 15225, 57200, 9270, 132, 1, 1, 924, 299880, 7043750, 5344800, 139968, 429, 1, 1, 3432, 6358044, 1112865264, 6327749750, 682612800, 2285073, 1430, 1, 1, 12870, 141858288, 203356067376, 11126161436292, 10411817136000, 118180104000, 39871926, 4862
Offset: 0

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Author

Andrew Howroyd, Feb 01 2024

Keywords

Comments

Definition (from A362167): Let Trees(n) be the set of unlabeled trees on n vertices (see A000055). Let T be in Trees(n+1), and let v be a vertex of T. Then a (k,T)-tour beginning at v is a walk that begins and ends at v and traverses each edge of T exactly 2*k times. We denote by N(k,T)(v) the number of (k,T)-tours beginning at v.
The hypergraph Catalan numbers C_k(n) are defined by C_k(n) = Sum_{trees T in T(n+1)} Sum_{vertices v in T} N(k,T)(v)/|Aut(T)|, where Aut(T) denotes the automorphism group of the tree T.
See the Gunnells reference for a full definition and additional information.

Examples

			Array begins:
n/k|   1       2            3              4                  5 ...
---+-----------------------------------------------------------------
 0 |   1       1            1              1                  1 ...
 1 |   1       1            1              1                  1 ...
 2 |   2       6           20             70                252 ...
 3 |   5      57          860          15225             299880 ...
 4 |  14     678        57200        7043750         1112865264 ...
 5 |  42    9270      5344800     6327749750     11126161436292 ...
 6 | 132  139968    682612800 10411817136000 255654847841227632 ...
  ...
		

Crossrefs

Row 2 is A000984.

Programs

  • PARI
    \\ here L(k,n) is k-th column of A060540 as g.f.
    L(k,n)={sum(n=1, n, (n*k)!*x^n/(k!^n*n!), O(x*x^n))}
    HypCatColGf(k,n)={my(p=L(k,n)); 1 + subst(p, x, serreverse(x^2/p))}
    M(n,m=n+1)={Mat(vector(m, k, Col(HypCatColGf(k,n))))}
    { my(A=M(7,5)); for(i=1, matsize(A)[1], print(A[i,])) }

Formula

G.f. of column k: 1 + B_k(Series_Reversion(x^2/B_k(x))) where B_k(x) is the g.f. of column k of A060540.

A370363 Number A(n,k) of partitions of [k*n] into n sets of size k having at least one set of consecutive numbers whose maximum (if k>0) is a multiple of k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 7, 1, 1, 0, 1, 1, 28, 45, 1, 1, 0, 1, 1, 103, 1063, 401, 1, 1, 0, 1, 1, 376, 22893, 74296, 4355, 1, 1, 0, 1, 1, 1384, 503751, 13080721, 8182855, 56127, 1, 1, 0, 1, 1, 5146, 11432655, 2443061876, 15237712355, 1305232804, 836353, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Feb 16 2024

Keywords

Examples

			A(3,2) = 7: 12|34|56, 12|35|46, 12|36|45, 13|24|56, 14|23|56, 15|26|34, 16|25|34.
Square array A(n,k) begins:
  0, 0,   0,     0,        0,          0, ...
  1, 1,   1,     1,        1,          1, ...
  1, 1,   1,     1,        1,          1, ...
  1, 1,   7,    28,      103,        376, ...
  1, 1,  45,  1063,    22893,     503751, ...
  1, 1, 401, 74296, 13080721, 2443061876, ...
		

Crossrefs

Columns k=0+1,2-3 give: A057427, A370253, A370358.
Rows n=0,1+2,3 give: A000004, A000012, A370487.
Main diagonal gives A370364.
Antidiagonal sums give A370365.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(k=0, signum(n), add(
          (-1)^(n-j+1)*binomial(n, j)*(k*j)!/(j!*k!^j), j=0..n-1))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);

Formula

A(n,k) = A060540(n,k) - A370366(n,k) for n,k >= 1.

A025037 Number of partitions of { 1, 2, ..., 5n } into sets of size 5.

Original entry on oeis.org

1, 1, 126, 126126, 488864376, 5194672859376, 123378675083039376, 5721809435651034101376, 470624547891733205872277376, 63887753000850674430367526069376, 13536281554808237495608549953475109376, 4280862577989659916223699531336456815269376
Offset: 0

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Author

Keywords

Crossrefs

Column k=5 of A060540.

Programs

  • Magma
    [Factorial(5*n)/(Factorial(n)*Factorial(5)^n): n in [0..10]]; // Vincenzo Librandi, Jun 26 2012
  • Mathematica
    Table[(5n)!/(n!(5!)^n),{n,0,10}] (* Vincenzo Librandi, Jun 26 2012 *)
  • Sage
    [rising_factorial(n+1,4*n)/120^n for n in (0..15)] # Peter Luschny, Jun 26 2012
    

Formula

a(n) = (5n)!/(n!(5!)^n). - Christian G. Bower, Sep 15 1998
a(n) ~ 5^(4*n+1/2) * (n/e)^(4*n) / 24^n. - Amiram Eldar, Aug 28 2025

Extensions

a(0) from Peter Luschny, Apr 24 2023

A322252 a(0) = 1 and a(n) = (5*n)!/(5!*n!^5) for n > 0.

Original entry on oeis.org

1, 1, 945, 1401400, 2546168625, 5194672859376, 11423951396577720, 26478825654361766400, 63805953776276649848625, 158421985022100255941485000, 402789797982510165934296910320, 1044048983553856888083223814102400, 2749848597736878877579660426025283000
Offset: 0

Views

Author

Seiichi Manyama, Nov 30 2018

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [Factorial(5*n)/(120*Factorial(n)^5):n in [1..12]]; // Marius A. Burtea, Feb 18 2020
  • Mathematica
    a[n_]:=(5*n)!/(5!*n!^5); Array[a, 20] (* or *) CoefficientList[Series[HypergeometricPFQ[{1/5, 2/5, 3/5, 4/5}, {1, 1, 1}, 3125 x]/(120 x) , {x, 0, 20}], x] (* Stefano Spezia, Dec 01 2018 *)

Formula

O.g.f.: F({1/5, 2/5, 3/5, 4/5}, {1, 1, 1}, 3125*x)/(120*x), where F is the generalized hypergeometric function. - Stefano Spezia, Dec 01 2018
a(n) = (1/5!)*A008978(n) for n >= 1. - Peter Bala, Feb 18 2020

A370366 Number A(n,k) of partitions of [k*n] into n sets of size k having no set of consecutive numbers whose maximum (if k>0) is a multiple of k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 2, 0, 0, 1, 0, 9, 8, 0, 0, 1, 0, 34, 252, 60, 0, 0, 1, 0, 125, 5672, 14337, 544, 0, 0, 1, 0, 461, 125750, 2604732, 1327104, 6040, 0, 0, 1, 0, 1715, 2857472, 488360625, 2533087904, 182407545, 79008, 0, 0
Offset: 0

Views

Author

Alois P. Heinz, Feb 16 2024

Keywords

Examples

			A(2,3) = 9: 124|356, 125|346, 126|345, 134|256, 135|246, 136|245, 145|236, 146|235, 156|234.
Square array A(n,k) begins:
  1, 1,   1,       1,          1,             1, ...
  0, 0,   0,       0,          0,             0, ...
  0, 0,   2,       9,         34,           125, ...
  0, 0,   8,     252,       5672,        125750, ...
  0, 0,  60,   14337,    2604732,     488360625, ...
  0, 0, 544, 1327104, 2533087904, 5192229797500, ...
		

Crossrefs

Columns k=0+1,2-3 give: A000007, A053871, A370357.
Rows n=0-2 give: A000012, A000004, A010763(n-1) for k>0.
Main diagonal gives A370367.
Antidiagonal sums give A370368.

Programs

  • Maple
    A:= proc(n, k) `if`(k=0,`if`(n=0, 1, 0), add(
          (-1)^(n-j)*binomial(n, j)*(k*j)!/(j!*k!^j), j=0..n))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);

Formula

A(n,k) = A060540(n,k) - A370363(n,k) for n,k >= 1.

A370407 Total sum over all j in [n] of the number of partitions of [j*(n-j)] into (n-j) sets of size j.

Original entry on oeis.org

1, 2, 3, 4, 7, 29, 424, 22250, 4166012, 3228619112, 9836415861419, 148021077093705105, 9516162824804128833773, 3369338041967340627557507931, 5792066385997100947453116161699033, 55416753515944143275546728017602371379095
Offset: 0

Views

Author

Alois P. Heinz, Feb 17 2024

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> add(`if`(j=n, 1, (j*(n-j))!/((n-j)!^j*j!)), j=0..n):
    seq(a(n), n=0..15);

Formula

a(n) = A370365(n) + A370368(n).
a(n) = Sum_{j=0..n} A361948(j,n-j).
a(n) mod 2 = A275973(n-1) for n>=2.

A025038 Number of partitions of { 1, 2, ..., 6n } into sets of size 6.

Original entry on oeis.org

1, 1, 462, 2858856, 96197645544, 11423951396577720, 3708580189773818399040, 2779202577056119960603777920, 4263127221846887596248598498826880, 12233832241625685631640659383106015132800, 61247286460823449786646954166350590676638060800
Offset: 0

Views

Author

Keywords

Crossrefs

Column k=6 of A060540.

Programs

  • Mathematica
    Table[Pochhammer[n + 1, 5*n]/6!^n, {n, 0, 15}] (* Paolo Xausa, Aug 08 2024 *)
  • Sage
    [rising_factorial(n+1,5*n)/720^n for n in (0..15)] # Peter Luschny, Jun 26 2012

Formula

a(n) = (6n)!/(n!(6!)^n). - Christian G. Bower, Sep 15 1998
a(n) ~ 2^(2*n+1/2) * 3^(4*n+1/2) * (n/e)^(5*n) / 5^n. - Amiram Eldar, Aug 28 2025

Extensions

a(0) and a(10) from Andrew Howroyd, Feb 26 2018

A025040 Number of partitions of { 1, 2, ..., 8n } into sets of size 8.

Original entry on oeis.org

1, 1, 6435, 1577585295, 4148378852099625, 63805953776276649848625, 4012852078114749147678149338875, 814318942973348333484015877548157809375, 450538787986875167583433232345723106006796340625, 599167346385710947364525167684682505182168120225201390625
Offset: 0

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Author

Keywords

Crossrefs

Column k=8 of A060540.

Programs

  • Mathematica
    Table[Pochhammer[n + 1, 7*n]/8!^n, {n, 0, 10}] (* Paolo Xausa, Aug 08 2024 *)

Formula

a(n) = (8n)!/(n!(8!)^n). - Christian G. Bower, Sep 15 1998
a(n) ~ 2^(17*n+3/2) * (n/e)^(7*n) / 315^n. - Amiram Eldar, Aug 28 2025

Extensions

a(0)=1 from Andrew Howroyd, Feb 26 2018

A025041 Number of partitions of { 1, 2, ..., 9n } into sets of size 9.

Original entry on oeis.org

1, 1, 24310, 37978905250, 893864677761055000, 158421985022100255941485000, 140413003088367308737750586624350000, 474750200441159213998774295008486246570750000, 5050927030108676304976606530597710043478228399030000000
Offset: 0

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Author

Keywords

Crossrefs

Column k=9 of A060540.

Programs

  • Mathematica
    Table[Pochhammer[n + 1, 8*n]/9!^n, {n, 0, 10}] (* Paolo Xausa, Aug 08 2024 *)

Formula

a(n) = (9*n)!/(n!*(9!)^n). - Christian G. Bower, Sep 15 1998
a(n) ~ 3^(14*n+1) * (n/e)^(8*n) / 4480^n. - Amiram Eldar, Aug 28 2025

Extensions

a(0)=1 from Andrew Howroyd, Feb 26 2018

A025042 Number of partitions of { 1, 2, ..., 10n } into sets of size 10.

Original entry on oeis.org

1, 1, 92378, 925166131890, 196056702961398759480, 402789797982510165934296910320, 5061324188732823772720935900249118313520, 286835743456312434671347570864365730919777702885760, 59034098562652855324502713832050720577190114808212674462486400
Offset: 0

Views

Author

Keywords

Crossrefs

Column k=10 of A060540.

Programs

  • Mathematica
    Table[Pochhammer[n + 1, 9*n]/10!^n, {n, 0, 10}] (* Paolo Xausa, Aug 08 2024 *)

Formula

a(n) = (10n)!/(n!(10!)^n). - Christian G. Bower, Sep 15 1998
a(n) = a(n-1)*binomial(10*n-1,9). - Christian Krause, Dec 07 2023
a(n) ~ 2^(2*n+1/2) * 5^(8*n+1/2) * (n/e)^(9*n) / 567^n. - Amiram Eldar, Aug 28 2025

Extensions

a(0)=1 from Andrew Howroyd, Feb 26 2018
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