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 1-10 of 16 results. Next

A060854 Array T(m,n) read by antidiagonals: T(m,n) (m >= 1, n >= 1) = number of ways to arrange the numbers 1,2,...,m*n in an m X n matrix so that each row and each column is increasing.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 5, 5, 1, 1, 14, 42, 14, 1, 1, 42, 462, 462, 42, 1, 1, 132, 6006, 24024, 6006, 132, 1, 1, 429, 87516, 1662804, 1662804, 87516, 429, 1, 1, 1430, 1385670, 140229804, 701149020, 140229804, 1385670, 1430, 1, 1, 4862, 23371634, 13672405890, 396499770810, 396499770810, 13672405890, 23371634, 4862, 1
Offset: 1

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Author

R. H. Hardin, May 03 2001

Keywords

Comments

Multidimensional Catalan numbers; a special case of the "hook-number formula".
Number of paths from (0,0,...,0) to (n,n,...,n) in m dimensions, all coordinates increasing: if (x_1,x_2,...,x_m) is on the path, then x_1 <= x_2 <= ... <= x_m. Number of ways to label an n by m array with all the values 1..n*m such that each row and column is strictly increasing. Number of rectangular Young Tableaux. Number of linear extensions of the n X m lattice (the divisor lattice of a number having exactly two prime divisors). - Mitch Harris, Dec 27 2005
Given m*n lines in a {(m + 1)(n - 1)}-dimensional space, T(m, n) is the number of {n*(m-1)-1}-dimensional spaces cutting these lines in points (see Fontanari and Castelnuovo). - Stefano Spezia, Jun 19 2022

Examples

			Array begins:
  1,   1,     1,         1,            1,                1, ...
  1,   2,     5,        14,           42,              132, ...
  1,   5,    42,       462,         6006,            87516, ...
  1,  14,   462,     24024,      1662804,        140229804, ...
  1,  42,  6006,   1662804,    701149020,     396499770810, ...
  1, 132, 87516, 140229804, 396499770810, 1671643033734960, ...
		

References

  • Guido Castelnuovo, Numero degli spazi che segano più rette in uno spazio ad n dimensioni, Rendiconti della R. Accademia dei Lincei, s. IV, vol. V, 4 agosto 1889. In Guido Castelnuovo, Memorie scelte, Zanichelli, Bologna 1937, pp. 55-64 (in Italian).
  • R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 7.23.19(b).

Crossrefs

Rows give A000108 (Catalan numbers), A005789, A005790, A005791, A321975, A321976, A321977, A321978.
Diagonals give A039622, A060855, A060856.
Cf. A227578. - Alois P. Heinz, Jul 18 2013
Cf. A321716.

Programs

  • Maple
    T:= (m, n)-> (m*n)! * mul(i!/(m+i)!, i=0..n-1):
    seq(seq(T(n, 1+d-n), n=1..d), d=1..10);
  • Mathematica
    maxm = 10; t[m_, n_] := Product[k!, {k, 0, n - 1}]*(m*n)! / Product[k!, {k, m, m + n - 1}]; Flatten[ Table[t[m + 1 - n, n], {m, 1, maxm}, {n, 1, m}]] (* Jean-François Alcover, Sep 21 2011 *)
    Table[ BarnesG[n+1]*(n*(m-n+1))!*BarnesG[m-n+2] / BarnesG[m+2], {m, 1, 10}, {n, 1, m}] // Flatten (* Jean-François Alcover, Jan 30 2016 *)
  • PARI
    {A(i, j) = if( i<0 || j<0, 0, (i*j)! / prod(k=1, i+j-1, k^vecmin([k, i, j, i+j-k])))}; /* Michael Somos, Jan 28 2004 */

Formula

T(m, n) = 0!*1!*..*(n-1)! *(m*n)! / ( m!*(m+1)!*..*(m+n-1)! ).
T(m, n) = A000142(m*n)*A000178(m-1)*A000178(n-1)/A000178(m+n-1) = A000142(A004247(m, n)) * A007318(m+n, n)/A009963(m+n, n). - Henry Bottomley, May 22 2002

Extensions

More terms from Frank Ellermann, May 21 2001

A079478 Coefficient of x^0 in P(n,x) = (Product_{i=0..n-1} i!^2)/matdet(M(n)) of degree n^2 where M(n) is the n X n matrix m(i,j) = 1/(i+j+x).

Original entry on oeis.org

1, 2, 72, 172800, 60963840000, 5574884681318400000, 205619158526859285626880000000, 4394314874750658447092552646524928000000000, 73955304765761130113502867875624106401967636480000000000000
Offset: 0

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Author

Benoit Cloitre, Jan 15 2003

Keywords

Comments

Product of all matrix elements of n X n matrix M(i,j) = i+j (i,j=1..n). - Alexander Adamchuk, Apr 12 2006

Examples

			Determinant of M(2) is 1/(x^4 + 12*x^3 + 53*x^2 + 102*x + 72) hence a(2)=72.
		

Crossrefs

Cf. A011379.
Central column in triangle A009963.

Programs

  • Maple
    seq(mul(mul(k+j,j=1..n), k=1..n), n=0..8); # Zerinvary Lajos, Jun 01 2007
  • Mathematica
    Table[Product[Product[(i+j),{i,1,n}],{j,1,n}],{n,0,10}] (* Alexander Adamchuk, Apr 12 2006 *)
    Table[BarnesG[2*n+2] / BarnesG[n+2]^2, {n,0,10}] (* Vaclav Kotesovec, Feb 28 2019 *)
  • PARI
    a(n)=(n+1)*prod(i=0,n,(n+i)!)/prod(i=1,n+1,i!)
    
  • PARI
    a(n) = prod(i=1, n, prod(j=1, n, i+j)); \\ Michel Marcus, Feb 27 2019
    
  • Python
    from math import prod, factorial
    def A079478(n): return prod(i+j for i in range(1,n) for j in range(i+1,n+1))**2*factorial(n)<Chai Wah Wu, Nov 26 2023

Formula

a(n) = (n+1)*(Product_{i=0..n} (n+i)!)/Product_{i=1..n+1} i!.
a(n) = A000178(2n)/A000178(n)^2, i.e., "central supercombinations" by analogy with A000984. - Henry Bottomley, May 14 2005
a(n) = Product_{j=1..n} Product_{i=1..n} (i + j). - Alexander Adamchuk, Apr 12 2006
Asymptotic: a(n) ~ (2*n+1)^(2*n^2 + 2*n + 5/12)*(n+1)^(-n^2 - 2*n - 5/6) * exp(-zeta'(-1) - (3/2)*n^2 + 3/4)/(sqrt(2*Pi)). - Peter Luschny, Nov 26 2012
a(n) = BarnesG(2*n+2) / BarnesG(n+2)^2. - Vaclav Kotesovec, Feb 28 2019
a(n) ~ A * 2^(2*n*(n+1) - 1/12) * n^(n^2 - 5/12) / (sqrt(Pi) * exp(3*n^2/2 + 1/12)), where A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Dec 04 2023

A010796 a(n) = n!*(n+1)!/2.

Original entry on oeis.org

1, 6, 72, 1440, 43200, 1814400, 101606400, 7315660800, 658409472000, 72425041920000, 9560105533440000, 1491376463216640000, 271430516305428480000, 57000408424139980800000, 13680098021793595392000000, 3720986661927857946624000000
Offset: 1

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Author

Keywords

Comments

Column 2 in triangle A009963.
a(n) = A078740(n, 2), first column of (3, 2)-Stirling2 array.
Also the number of undirected Hamiltonian paths in the complete bipartite graph K_{n,n+1}. - Eric W. Weisstein, Sep 03 2017
Also, the number of undirected Hamiltonian cycles in the complete bipartite graph K_{n+1,n+1}. - Pontus von Brömssen, Sep 06 2022

Crossrefs

Main diagonal of A291909.

Programs

  • Magma
    [Factorial(n)* Factorial(n+1) / 2: n in [1..20]]; // Vincenzo Librandi, Jun 11 2013
    
  • Mathematica
    Table[n! (n + 1)! / 2, {n, 1, 20}] (* Vincenzo Librandi, Jun 11 2013 *)
    Times@@@Partition[Range[20]!,2,1]/2 (* Harvey P. Dale, Jul 04 2017 *)
  • PARI
    for(n=1,30, print1(n!*(n+1)!/2, ", ")) \\ G. C. Greubel, Feb 07 2018

Formula

a(n) = 2^(n-1) * A006472(n+1).
a(n) = A010790(n)/2.
E.g.f.: (hypergeom([1, 2], [], x)-1)/2.
a(n) = Product_{k=1..n-1} (k^2+3*k+2). - Gerry Martens, May 09 2016
E.g.f.: x*hypergeom([1, 3], [], x). - Robert Israel, May 09 2016
From Amiram Eldar, Jun 25 2022: (Start)
Sum_{n>=1} 1/a(n) = 2*(BesselI(1, 2) - 1).
Sum_{n>=1} (-1)^(n+1)/a(n) = 2*(1 - BesselJ(1, 2)). (End)

A090441 Symmetric triangle of certain normalized products of decreasing factorials.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 6, 12, 6, 1, 1, 24, 144, 144, 24, 1, 1, 120, 2880, 8640, 2880, 120, 1, 1, 720, 86400, 1036800, 1036800, 86400, 720, 1, 1, 5040, 3628800, 217728000, 870912000, 217728000, 3628800, 5040, 1, 1, 40320, 203212800, 73156608000
Offset: 0

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Author

Wolfdieter Lang, Dec 23 2003

Keywords

Comments

Similar to, but different from, superfactorial Pascal triangle A009963.
A009963(n,m) = (Product_{p=0..m-1} (n-p)!)/superfac(m) with n >= m >= 0, otherwise 0.
From Natalia L. Skirrow, Apr 13 2025 (Start)
Denoting this sequence as the superbinomial sb(n,k), the hook length formula for a j X k rectangular Young tableau states the number of configurations of j*k distinct numbers such that each row and column is strictly increasing is (j*k)!/sb(j+k,j), ie. 1/sb(j+k,j) is the probability that a random permutation is a Young tableau.
Meanwhile, if the numbers are placed into the array with repetition, but the columns are still strictly increasing, there are c(n,j,k) = sb(n+1,j+k)/(sb(n+1-j,k)*sb(n+1-k,j)) configurations.
If the strict criterion is relaxed to monotonic, this becomes C(n,j,k) = sb(n-1+j+k,j+k)/(sb(n-1+j,j)*sb(n-1+k,k)).
By proposition 13.2(i) of Stanley's PhD thesis, for fixed j,k, c(n,j,k) and C(n,j,k) are polynomials in n of degree j*k, and c(n,j,k) = (-1)^(j*k)*C(-n,j,k).
For example, c(n,1,k)=(n choose k) and C(n,1,k)=(n+k-1 choose k), while c(n,2,k) = N(n,k+1) and C(n,2,k) = N(n+k,k+1), so the binomial coefficients and Narayana numbers N=A001263 obey the dualities (under continuation as polynomials) (n choose k) = (-1)^k*(k-1-n choose k) and N(n,k) = N(k-1-n,k).
(End)

Examples

			Rows for n = 0, 1, 2, 3, ...:
  1;
  1,  1;
  1,  1,  1;
  1,  2,  2,  1;
  1,  6, 12,  6,  1;
  ...
		

Crossrefs

Column sequences give: A000012 (powers of 1), A000142 (factorials), A010790, A090443-4, etc.
Cf. A090445 (row sums), A090446 (alternating row sums).

Programs

  • PARI
    spf(n) = prod(k=2, n, k!);
    T(n,m) = spf(n-1)/spf(m-1)/spf(n-m-1);
    row(n) = vector(n+1, k, T(n, k-1)); \\ Michel Marcus, Apr 13 2025

Formula

a(n, m) = 0 if n < m;
a(n, m) = 1 if m = 0 or m = n;
a(n, m) = (Product_{p=1..m} (n-p)!)/superfac(m-1) if n >= 0, 1 <= m <= n+1, where superfac(n) := A000178(n), n >= 0, (superfactorials).
a(n, m) = superfac(n-1)/superfac(m-1)/superfac(n-m-1)
With offset 1, equals ConvOffsStoT transform of the factorials, A000142: (1, 1, 2, 6, 24, ...); e.g., ConvOffs transform of (1, 1, 2, 6) = (1, 6, 12, 6, 1). - Gary W. Adamson, Apr 21 2008

Extensions

OFFSET changed from -1 to 0 by Natalia L. Skirrow, Apr 13 2025

A193520 a(n) = Sum_{k=0..n} G(n)/(G(k)*G(n-k)) where G(n) = Product_{k=0..n} k!.

Original entry on oeis.org

1, 2, 4, 14, 122, 3122, 260642, 76214882, 85552669442, 381014246511362, 7442029915221081602, 632869669701185574873602, 264542347321693265938488883202, 517169258108069965039831739271321602, 5495073385198979486456081260457854269542402
Offset: 0

Views

Author

Paul D. Hanna, Jul 29 2011

Keywords

Examples

			Let F(x) = 1 + x + x^2/(1!*2!) + x^3/(1!*2!*3!) + x^4/(1!*2!*3!*4!) +...+ x^n/G(n) +...
then
F(x)^2 = 1 + 2*x + 4*x^2/(1!*2!) + 14*x^3/(1!*2!*3!) + 122*x^4/(1!*2!*3!*4!) + 3122*x^5/(1!*2!*3!*4!*5!) +...+ a(n)*x^n/G(n) +...
Illustration of initial terms:
a(3) = 1 + 3! + 3! + 1 = 14;
a(4) = 1 + 4! + 4!*3!/2! + 4! + 1 = 122;
a(5) = 1 + 5! + 5!*4!/2! + 5!*4!/2! + 5! + 1 = 3122;
a(6) = 1 + 6! + 6!*5!/2! + 6!*5!*4!/(3!*2!) + 6!*5!/2! + 6! + 1 = 260642; ...
		

Crossrefs

Row sums of A009963.

Programs

  • Magma
    A009963:= func< n,k | (1/Factorial(n+1))*(&*[ Factorial(n-j+1)/Factorial(j): j in [0..k]]) >;
    A193520:= func< n | (&+[A009963(n,j): j in [0..n]]) >;
    [A193520(n): n in [0..20]]; // G. C. Greubel, Jan 05 2022
  • Mathematica
    Table[Sum[BarnesG[n+2] / (BarnesG[k+2] * BarnesG[n-k+2]), {k, 0, n}], {n, 0, 15}] (* Vaclav Kotesovec, Mar 04 2019 *)
  • PARI
    {a(n)=sum(k=0,n,prod(j=0,n,j!)/(prod(j=0,k,j!)*prod(j=0,n-k,j!)))}
    
  • PARI
    {a(n)=prod(k=1,n,k!)*polcoeff((sum(m=0,n+1,x^m/prod(k=0,m,k!)+x*O(x^n))^2),n)}
    
  • Sage
    from mpmath import mp
    mp.dps = 98; mp.pretty = True
    def superbinomial(n,k):
        return mp.superfac(n)/(mp.superfac(k)*mp.superfac(n-k))
    def A193520(n): return add(superbinomial(n,k) for k in (0..n))
    [int(A193520(n)) for n in (0..14)]  # Peter Luschny, Nov 28 2012
    

Formula

G.f.: A(x) = ( Sum_{n>=0} x^n/G(n) )^2 where A(x) = Sum_{n>=0} a(n)*x^n/G(n), and G(n) = Product_{k=0..n} k!.
a(n) ~ 2^(n^2/4 + n - 5*(-1)^n/8 + 23/24) * n^(n^2/4 + (-1)^n/8 - 13/24) / (sqrt(Pi) * exp(3*n^2/8 + Zeta'(-1))). - Vaclav Kotesovec, Mar 04 2019

A010797 a(n) = n! * (n+1)! * (n+2)! / (2! * 3!).

Original entry on oeis.org

1, 24, 1440, 172800, 36288000, 12192768000, 6145155072000, 4424511651840000, 4380266535321600000, 5781951826624512000000, 9921829334487662592000000, 21669275266521055100928000000
Offset: 1

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Author

Keywords

Crossrefs

Column 3 in triangle A009963.

Programs

  • Mathematica
    Times@@@Partition[Range[15]!,3,1]/(2!3!) (* Harvey P. Dale, Aug 06 2022 *)

Extensions

Offset changed to 1 by Seiichi Manyama, Aug 14 2023

A010798 a(n) = n! * (n+1)! * (n+2)! * (n+3)! / (2! * 3! * 4!).

Original entry on oeis.org

1, 120, 43200, 36288000, 60963840000, 184354652160000, 929147446886400000, 7358847779340288000000, 87423111618562621440000000, 1500180595374534583910400000000, 36040338623277818843863449600000000
Offset: 1

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Author

Keywords

Crossrefs

Column 4 in triangle A009963.

Programs

  • Mathematica
    #/(2!3!4!)&/@Times@@@Partition[Range[20]!,4,1] (* Harvey P. Dale, Jul 29 2022 *)

Extensions

Offset changed to 1 by Seiichi Manyama, Aug 14 2023

A010799 a(n) = n!*(n+1)!*(n+2)!*(n+3)!*(n+4)! / ( 2!*3!*4!*5! ).

Original entry on oeis.org

1, 720, 1814400, 12192768000, 184354652160000, 5574884681318400000, 309071606732292096000000, 29374165503837040803840000000, 4536546120412592581745049600000000
Offset: 1

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Author

Keywords

Crossrefs

Column 5 in triangle A009963.

Programs

  • Mathematica
    With[{c=Times@@(Range[2,5]!),l=Times@@@Partition[Range[20]!,5,1]}, #/c&/@l] (* Harvey P. Dale, Nov 10 2011 *)

Extensions

Offset changed to 1 by Seiichi Manyama, Aug 14 2023

A010800 a(n) = n! * (n+1)! * (n+2)! * (n+3)! * (n+4)! * (n+5)! / (2! * 3! * 4! * 5! * 6!).

Original entry on oeis.org

1, 5040, 101606400, 6145155072000, 929147446886400000, 309071606732292096000000, 205619158526859285626880000000, 254046582743105184577722777600000000, 549289359343832305886569080815616000000000, 1979419135331434097492840339627153817600000000000
Offset: 1

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Author

Keywords

Crossrefs

Column 6 in triangle A009963.

Programs

  • Mathematica
    Module[{nn=20,c=Times@@(Range[2,6]!)},(Times@@@Partition[ Range[ nn]!, 6,1])/c] (* Harvey P. Dale, Jul 29 2015 *)

Extensions

More terms from Harvey P. Dale, Jul 29 2015
Offset changed to 1 by Seiichi Manyama, Aug 14 2023

A107252 a(n) = Product_{k=0..n-1} (n+k)!/(k+1)!.

Original entry on oeis.org

1, 1, 6, 1440, 36288000, 184354652160000, 309071606732292096000000, 254046582743105184577722777600000000, 142518177743863255019484504453155074867200000000000
Offset: 0

Views

Author

Henry Bottomley, May 14 2005

Keywords

Examples

			a(3) = 1!*2!*3!*4!*5!/(1!*2!*3!*1!*2!) = 34560/24 = 1440.
		

Crossrefs

Programs

  • Magma
    [1] cat [(&*[Factorial(n+k)/Factorial(k+1): k in [0..n-1]]): n in [1..10]]; // G. C. Greubel, May 21 2019
    
  • Mathematica
    Table[Product[(n+k)!/(k+1)!,{k,0,n-1}],{n,0,10}] (* Alexander Adamchuk, Jul 10 2006 *)
    a[n_] := (BarnesG[1 + 2 n] n! ((BarnesG[2 + n] Gamma[2 + n])/ BarnesG[3 + n])^(-1 + n))/BarnesG[2 + n]^2; Table[a[n], {n, 0, 10}] (* Peter Luschny, May 20 2019 *)
  • PARI
    {a(n) = prod(k=0,n-1, (n+k)!/(k+1)!)}; \\ G. C. Greubel, May 21 2019
    
  • Sage
    [product(factorial(n+k)/factorial(k+1) for k in (0..n-1)) for n in (0..10)] # G. C. Greubel, May 21 2019

Formula

a(n) = (n+1)!*(n+2)!*...*(2n-1)!/(1!*2!*...*(n-1)!).
a(n) = A000178(2n-1)/(A000178(n)*A000178(n-1)).
a(n) = A079478(n)/A001813(n).
a(n) = A079478(n-1)*A006963(n+1).
a(n) = A107251(n)/A000108(n).
a(n) = A107251(n-1)*A009445(n-1).
a(n) = A107254(n)/A000142(n).
a(n) = A009963(2n-1, n-1).
a(n) = A009963(2n-1, n).
a(n) = (G(1+2*n)*n!*((G(2+n)*Gamma(2+n))/G(3+n))^(n-1))/G(2+n)^2, where G(x) is the Barnes G function. - Peter Luschny, May 20 2019
a(n) ~ A * 2^(2*n^2 - 7/12) * n^(n^2 - n - 5/12) / (sqrt(Pi) * exp(3*n^2/2 - n + 1/12)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, May 21 2019
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