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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A225816 Square array A(n,k) = (k!)^n, n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 6, 4, 1, 1, 1, 24, 36, 8, 1, 1, 1, 120, 576, 216, 16, 1, 1, 1, 720, 14400, 13824, 1296, 32, 1, 1, 1, 5040, 518400, 1728000, 331776, 7776, 64, 1, 1, 1, 40320, 25401600, 373248000, 207360000, 7962624, 46656, 128, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 29 2013

Keywords

Comments

A(n,k) is the determinant of the k X k matrix M = [Stirling2(n+i,j)] for 1<=i,j<=k. A(2,3) = det([1,3,1; 1,7,6; 1,15,25]) = 36.
A(n,k) is the determinant of the symmetric k X k matrix M = [sigma_n(gcd(i,j))] for 1<=i,j<=k. A(2,3) = det([1,1,1; 1,5,1; 1,1,10]) = 36.
A(n,k) is (-1)^(n*k) times the determinant of the n X n matrix M = [Stirling1(k+i,j)] for 1<=i,j<=n. A(2,3) = (-1)^(2+3) * det([-6,11; 24,-50]) = 36.
A(n,k) is the number of lattice paths from {n}^k to {0}^k using steps that decrement one component by 1 such that for each point (p_1,p_2,...,p_k) we have abs(p_i-p_j) <= 1 for 1<=i,j<=k. A(2,3) = 36:
(1,2,2)-(1,1,2) (0,1,1)-(0,0,1)
/ X \ / X \
(2,2,2)-(2,1,2) (1,2,1)-(1,1,1)-(1,0,1) (0,1,0)-(0,0,0).
\ X / \ X /
(2,2,1) (2,1,1) (1,1,0) (1,0,0)
A(n,k) is the number of set partitions of [k*(n+1)] into k blocks of size n+1 such that the elements of each block are distinct mod n+1. A(2,3) = 36: 123|456|789, 126|345|789, ..., 189|234|567, 189|246|357.

Examples

			Square array A(n,k) begins:
  1, 1,  1,    1,       1,           1, ...
  1, 1,  2,    6,      24,         120, ...
  1, 1,  4,   36,     576,       14400, ...
  1, 1,  8,  216,   13824,     1728000, ...
  1, 1, 16, 1296,  331776,   207360000, ...
  1, 1, 32, 7776, 7962624, 24883200000, ...
		

Crossrefs

Columns k=0+1, 2-4 give: A000012, A000079, A000400, A009968.
Rows n=0-4 give: A000012, A000142, A001044, A000442, A134375.
Main diagonal gives: A036740.

Programs

  • Maple
    A:= (n, k)-> k!^n:
    seq(seq(A(n,d-n), n=0..d), d=0..12);

Formula

A(n,k) = (k!)^n.
A(n,k) = k^n * A(n,k-1) for k>0, A(n,0) = 1.
A(n,k) = k! * A(n-1,k) for n>0, A(0,k) = 1.
G.f. of column k: 1/(1-k!*x).

A134372 a(n) = ((2n)!)^2.

Original entry on oeis.org

1, 4, 576, 518400, 1625702400, 13168189440000, 229442532802560000, 7600054456551997440000, 437763136697395052544000000, 40990389067797283140009984000000, 5919012181389927685417441689600000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n)!)^(2), {n, 0, 10}]
    ((2*Range[0,20])!)^2 (* Harvey P. Dale, Jul 14 2011 *)
  • PARI
    a(n) = ((2*n)!)^2; \\ Michel Marcus, Nov 16 2020

Formula

From Amiram Eldar, Nov 16 2020: (Start)
Sum_{n>=0} 1/a(n) = A334379.
Sum_{n>=0} (-1)^n/a(n) = A334632. (End)

A134370 a(n) = ((2n+1)!)^(n+2).

Original entry on oeis.org

1, 216, 207360000, 3252016064102400000, 2283380023591730815784976384000000, 161469323688736156802100136913438716723200000000000000, 2260697901194635682690248130915498742378267539496871953338204160000000000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n+1)!)^(n + 2), {n, 0, 10}]

Formula

a(n) ~ 2^(2*(n+1)*(n+2)) * exp(13/24 - 2*n*(n+2)) * n^((n+2)*(4*n+3)/2) * Pi^(n/2 + 1). - Vaclav Kotesovec, Oct 26 2017

Extensions

Typo in a(6) corrected by Georg Fischer, Apr 10 2024

A134373 a(n) = ((2n)!)^3.

Original entry on oeis.org

1, 8, 13824, 373248000, 65548320768000, 47784725839872000000, 109903340320478724096000000, 662559760549147780765974528000000, 9159226129831418921308831875072000000000, 262435789155225791087396177124997988352000000000
Offset: 0

Views

Author

Artur Jasinski, Oct 22 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Table[((2n)!)^(3), {n, 0, 10}]
    ((2*Range[0, 10])!)^3 (* Harvey P. Dale, Jul 25 2016 *)
  • Sage
    [factorial(2*n)**3 for n in range(0,9)] # Stefano Spezia, Apr 22 2025

Extensions

Definition corrected by Harvey P. Dale, Jul 25 2016

A249677 Triangle, read by rows, with row n forming the coefficients in Product_{k=0..n} (1 + k^3*x).

Original entry on oeis.org

1, 1, 1, 1, 9, 8, 1, 36, 251, 216, 1, 100, 2555, 16280, 13824, 1, 225, 15055, 335655, 2048824, 1728000, 1, 441, 63655, 3587535, 74550304, 444273984, 373248000, 1, 784, 214918, 25421200, 1305074809, 26015028256, 152759224512, 128024064000, 1, 1296, 616326, 135459216, 14320729209, 694213330464, 13472453691584, 78340747014144, 65548320768000
Offset: 0

Views

Author

Paul D. Hanna, Nov 03 2014

Keywords

Comments

Column 1 forms the squares of the triangular numbers (A000537).
Main diagonal forms the cubes of the factorial numbers (A000442).
Row sums equal Product_{k=1..n} (k^3 + 1) = n!*Product_{k=1..n} (k*(k-1) + 1) = n!*A130032(n).

Examples

			Triangle begins:
  1;
  1, 1;
  1, 9, 8;
  1, 36, 251, 216;
  1, 100, 2555, 16280, 13824;
  1, 225, 15055, 335655, 2048824, 1728000;
  1, 441, 63655, 3587535, 74550304, 444273984, 373248000;
  1, 784, 214918, 25421200, 1305074809, 26015028256, 152759224512, 128024064000;
  1, 1296, 616326, 135459216, 14320729209, 694213330464, 13472453691584, 78340747014144, 65548320768000; ...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=polcoeff(prod(m=0,n,1 + m^3*x +x*O(x^n)),k)}
    for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))

A381161 a(n) = (10*n)!/((n!)^3*(2*n)!*(5*n)!).

Original entry on oeis.org

1, 15120, 3491888400, 1304290155168000, 601680868708529610000, 312696069714024464473125120, 175460887238127057573116837126400, 103865765423748548466734695459219968000, 63958974275578307119821712720619705931210000, 40596987692554701292235753375257230410967703200000
Offset: 0

Views

Author

Stefano Spezia, Feb 15 2025

Keywords

Comments

Calabi-Yau series number 2.

Crossrefs

Programs

  • Mathematica
    a[n_]:=(10n)!/((n!)^3*(2n)!*(5n)!); Array[a,10,0]

Formula

G.f.: hypergeom([1/10, 3/10, 7/10, 9/10], [1, 1, 1], 2^8*5^5*x).
a(n) ~ 9*2^(3+8*n)*5^(1+5*n)/((1 + 24*n)*(1 + 60*n)*Pi^2).

A381165 a(n) = Sum_{k=0..n} binomial(2*n,n)*binomial(n, k)*(5*k)!/((k!)^3*(2*k)!).

Original entry on oeis.org

1, 122, 114126, 169305620, 307902541870, 628881704226972, 1384648756554128604, 3213280613371692112392, 7752574653184355259506670, 19272593072633780827550508620, 49062146831202726778631520779476, 127331178560917294198014376933764792, 335791906923524740189894975371277920796
Offset: 0

Views

Author

Stefano Spezia, Feb 15 2025

Keywords

Comments

Calabi-Yau series number 128.

Crossrefs

Programs

  • Mathematica
    a[n_]:=Sum[Binomial[2n,n]Binomial[n, k](5k)!/((k!)^3*(2k)!), {k, 0, n}]; Array[a, 13, 0]

Formula

G.f.: hypergeom([1/5, 2/5, 3/5, 4/5], [1, 1, 1], 5^5*x/(1-4*x))/sqrt(1-4*x).
a(n) = binomial(2*n,n)*hypergeom([1/5, 2/5, 3/5, 4/5, -n], [1/2, 1, 1, 1], -5^5/4).
a(n) ~ 3^(n + 3/2) * 7^(n + 3/2) * 149^(n +3/2) / (4 * 5^7 * Pi^2 * n^2). - Vaclav Kotesovec, May 29 2025

A269947 Triangle read by rows, Stirling cycle numbers of order 3, T(n,n) = 1, T(n,k) = 0 if k<0 or k>n, otherwise T(n,k) = T(n-1,k-1)+(n-1)^3*T(n-1,k), for n>=0 and 0<=k<=n.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 8, 9, 1, 0, 216, 251, 36, 1, 0, 13824, 16280, 2555, 100, 1, 0, 1728000, 2048824, 335655, 15055, 225, 1, 0, 373248000, 444273984, 74550304, 3587535, 63655, 441, 1, 0, 128024064000, 152759224512, 26015028256, 1305074809, 25421200, 214918, 784, 1
Offset: 0

Views

Author

Peter Luschny, Mar 22 2016

Keywords

Examples

			Triangle starts:
1,
0, 1,
0, 1,       1,
0, 8,       9,       1,
0, 216,     251,     36,     1,
0, 13824,   16280,   2555,   100,   1,
0, 1728000, 2048824, 335655, 15055, 225, 1.
		

Crossrefs

Variant: A249677.
Cf. A007318 (order 0), A132393 (order 1), A269944 (order 2).

Programs

  • Maple
    T := proc(n, k) option remember;
        `if`(n=k, 1,
        `if`(k<0 or k>n, 0,
         T(n-1, k-1) + (n-1)^3*T(n-1, k))) end:
    for n from 0 to 6 do seq(T(n,k), k=0..n) od;
  • Mathematica
    T[n_, k_] := T[n, k] = Which[n == k, 1, k < 0 || k > n, 0, True, T[n - 1, k - 1] + (n - 1)^3 T[n - 1, k]];
    Table[T[n, k], {n, 0, 8}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jul 12 2019 *)

Formula

T(n,1) = ((n-1)!)^3 for n>=1 (cf. A000442).
T(n,n-1) = (n*(n-1)/2)^2 for n>=1 (cf. A000537).
Row sums: Product_{k=1..n} ((k-1)^3+1) for n>=0 (cf. A255433).

A316862 Expansion of 1/(Sum_{k>=0} (k!)^3 x^k).

Original entry on oeis.org

1, -1, -7, -201, -13351, -1697705, -369575303, -127249900617, -65286578868455, -47651775381867241, -47688241963081263175, -63505249400026210723209, -109775495351620406817045415, -241236985075124408660287423529, -662075390371447206867029299628807
Offset: 0

Views

Author

Seiichi Manyama, Jul 15 2018

Keywords

Crossrefs

1/(Sum_{k>=0} (k!)^b x^k): A167894 (b=1), A113871 (b=2), this sequence (b=3).
Cf. A000442.

Programs

  • Mathematica
    a[n_] := -Sum[(k!)^3*a[n - k], {k, n}]; a[0] = 1; Array[a, 15, 0] (* Robert G. Wilson v, Jul 15 2018 *)
    nmax = 20; CoefficientList[Series[1/Sum[k!^3 * x^k, {k, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 08 2020 *)

Formula

a(0) = 1, a(n) = -Sum_{k=1..n} (k!)^3 * a(n-k).
a(n) ~ -(n!)^3 * (1 - 2/n^3 - 13/n^6 - 39/n^7 - 78/n^8 - 518/n^9 - 3687/n^10 - ...). - Vaclav Kotesovec, Dec 08 2020

A351800 a(n) = [x^n] 1/Product_{j=1..n} (1 - j^3*x).

Original entry on oeis.org

1, 1, 73, 28800, 33120201, 83648533275, 393764054984212, 3103381708489548640, 37965284782803741391413, 681476650259874114533077575, 17184647574689079046814198039765, 588057239856779143071625300022102376, 26548105106818292578525347802793561068860
Offset: 0

Views

Author

Alois P. Heinz, Feb 19 2022

Keywords

Examples

			a(2) = (1*1)^3 + (1*2)^3 + (2*2)^3 = 1 + 8 + 64 = 73.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k=0, 1,
          add(b(j, k-1)*j^3, j=1..n))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..15);
  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - k^3*x), {k, 1, n}], {x, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, May 17 2025 *)

Formula

a(n) = Sum_{p in {1..n}^n : p_i <= p_{i+1}} Product_{j=1..n} p_j^3.
a(n) = A098436(2n-1,n-1) = A269948(2n,n).
a(n) ~ c * d^n * n^(3*n - 1/2), where d = 1.54371040458513693750053812318801418996889528987425... and c = 0.71526493063554190404119140313248864511356727815244... - Vaclav Kotesovec, May 13 2025
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