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 1-5 of 5 results.

A232788 A232773(n) / A006882(n): Permanent of the n X n matrix with elements [1,2,...,n^2], divided by n!!.

Original entry on oeis.org

1, 1, 5, 150, 6932, 965380, 143299890, 51176650000, 16737737386944, 11806879466638656, 7023172771916784000, 8447153882019234307200, 8134080139379917205277696, 15176253254155788712392633600, 21875035292051870323313614135440, 59270306784445546617788929301760000
Offset: 0

Views

Author

M. F. Hasler, Nov 30 2013

Keywords

Comments

Limit n->infinity a(n)^(1/n)/n^(5/2) = exp(-3/2). - Vaclav Kotesovec, Nov 08 2014

Crossrefs

Programs

  • Maple
    with(combinat):
    a:= n-> (-1)^n *add(n^k *stirling1(n, n-k)*stirling1(n+1, k+1)
            *(n-k)!* k!, k=0..n)/doublefactorial(n):
    seq(a(n), n=0..20);  # Alois P. Heinz, Dec 02 2013
  • Mathematica
    Flatten[{1,Table[(-1)^n*Sum[n^k*StirlingS1[n,n-k]*StirlingS1[n+1,k+1]*(n-k)!*k!,{k,0,n}]/n!!,{n,1,20}]}] (* Vaclav Kotesovec, Nov 08 2014 *)
  • PARI
    n->(-1)^n*sum(k=0,n,n^k*stirling(n,n-k)*stirling(n+1,k+1)*(n-k)!*k!)/A006882(n)

Extensions

a(0)=1 inserted by Alois P. Heinz, Dec 02 2013

A114533 Permanent of the n X n matrix with numbers prime(1),prime(2),...,prime(n^2) in order across rows.

Original entry on oeis.org

1, 2, 29, 3746, 1919534, 2514903732, 6571874957648, 30662862975835376, 228731722381012564816, 2641049525155781555257440, 43818773386947889568479502592, 1014966115357067575070490776083200, 31412851866841234377483875199638978304
Offset: 0

Views

Author

Simone Severini, Feb 15 2006

Keywords

Comments

Previous name was : "a(n) = permanent of the n X n matrix M defined as follows: if we concatenate the rows of M to form a vector v of length n^2, v_i is the i-th prime number".

Crossrefs

Programs

  • Maple
    with(LinearAlgebra):
    a:= n->`if`(n=0, 1, Permanent(Matrix(n, (i, j)->ithprime((i-1)*n+j)))):
    seq(a(n), n=0..12);  # Alois P. Heinz, Dec 23 2013
  • Mathematica
    a[n_] := Permanent[Table[Prime[(i-1)*n+j], {i, 1, n}, {j, 1, n}]]; a[0]=1; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 0, 12}] (* Jean-François Alcover, Jan 07 2016, adapted from Maple *)
    Join[{1},Table[Permanent[Partition[Prime[Range[n^2]],n]],{n,15}]] (* Harvey P. Dale, Aug 03 2019 *)
  • PARI
    permRWN(a)=n=matsize(a)[1]; if(n==1,return(a[1,1])); n1=n-1; sg=1; m=1; nc=0; in=vector(n); x=in; for(i=1,n,x[i]=a[i,n]-sum(j=1,n,a[i,j])/2); p=prod(i=1,n,x[i]); while(m,sg=-sg; j=1; if((nc%2)!=0,j++; while(in[j-1]==0,j++)); in[j]=1-in[j]; z=2*in[j]-1; nc+=z; m=nc!=in[n1]; for(i=1,n,x[i]+=z*a[i,j]); p+=sg*prod(i=1,n,x[i])); return(2*(2*(n%2)-1)*p)
    for(n=1,19,a=matrix(n,n,i,j,prime((i-1)*n+j)); print1(permRWN(a)", ")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), May 11 2007
    
  • PARI
    permRWNb(a)=n=matsize(a)[1];if(n==1,return(a[1,1]));sg=1;in=vectorv(n);x=in;x=a[,n]-sum(j=1,n,a[,j])/2;p=prod(i=1,n,x[i]);for(k=1,2^(n-1)-1,sg=-sg;j=valuation(k,2)+1;z=1-2*in[j];in[j]+=z;x+=z*a[,j];p+=prod(i=1,n,x[i],sg));return(2*(2*(n%2)-1)*p)
    for(n=1,23,a=matrix(n,n,i,j,prime((i-1)*n+j));print1(permRWNb(a)",")) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), May 15 2007
    
  • PARI
    {a(n) = matpermanent(matrix(n, n, i, j, prime((i-1)*n+j)))}
    for(n=0, 25, print1(a(n), ", ")) \\ Vaclav Kotesovec, Aug 13 2021

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 11 2007
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 15 2007
New name from Michel Marcus, Nov 30 2013
a(0) inserted and a(12) by Alois P. Heinz, Dec 23 2013

A204248 Permanent of the n-th principal submatrix of A002024.

Original entry on oeis.org

1, 1, 7, 126, 4276, 234300, 18877020, 2100159600, 308417610816, 57786899446080, 13452134426136000, 3808606484711952000, 1288711254432792833280, 513583129024901529834240, 238093035025913233419052800, 127039392937347095305900800000, 77298350216325487808699492352000
Offset: 0

Views

Author

Clark Kimberling, Jan 14 2012

Keywords

Comments

a(n) is permanent of Toeplitz matrix
n n-1 n-2 ... 3 2 1
n+1 n n-1 ... 4 3 2
n+2 n+1 n ... 5 4 3
.......
2n-1 2n-2 2n-3 ... n+2 n+1 n. - Vladimir Shevelev, Dec 01 2013

Examples

			From _Vladimir Shevelev_, Dec 01 2013: (Start)
a(3) = permanent ( 3 2 1 ) = 3*17 + 2*22 + 1*31 = 126.
                 ( 4 3 2 )
                 ( 5 4 3 )
and
a(3) = |stirling1(3,3)*stirling1(4,1)|*6*1 + |stirling1(3,2)*stirling1(4,2)|*2*1 + |stirling1(3,1)*stirling1(4,3)|*1*2 = 1*6*6*1 + 3*11*2*1 + 2*6*1*2 = 126. (End)
		

Crossrefs

Programs

  • Mathematica
    f[i_, j_] := i + j - 1;
    m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
    TableForm[m[8]] (* 8x8 principal submatrix *)
    Flatten[Table[f[i, n + 1 - i],
      {n, 1, 12}, {i, 1, n}]]  (* A002024 *)
    Join[{1},Table[Permanent[m[n]], {n, 1, 15}]]  (* A204248 *)
  • PARI
    a(n) = (-1)^n * sum(k=0, n-1, stirling(n, n-k) * stirling(n+1, k+1) * (n-k)! * k! ) /* Max Alekseyev, Dec 02 2013 */
    
  • Python
    from math import factorial
    from sympy.functions.combinatorial.numbers import stirling
    def A204248(n): return sum(stirling(n,n-k,kind=1)*stirling(n+1,k+1,kind=1)*factorial(n-k)*factorial(k) for k in range(n)) if n else 1 # Chai Wah Wu, Oct 16 2022
    
  • Python
    from math import factorial, comb
    from sympy.functions.combinatorial.numbers import stirling
    def A204248(n): return factorial(n)*stirling(m:=(n<<1)+1,n+1,kind=1)//comb(m,n) # Chai Wah Wu, Jun 08 2025

Formula

a(n) = (-1)^n * Sum_{k=0..n} Stirling1(n,n-k) * Stirling1(n+1,k+1) * (n-k)! * k!. - Vladimir Shevelev, Dec 01 2013
Limit n->infinity a(n)^(1/n)/n^2 = -2*c^2/(exp(2)*(1+2*c)) = 0.33230326707622..., where c = LambertW(-1,-1/(2*exp(1/2))) = -1.756431208626... - Vaclav Kotesovec, Dec 10 2013
a(n) ~ 2.531082868731093... * (-2*c^2/(exp(2)*(1+2*c)))^n * n^(2*n+1/2), where c = LambertW(-1,-1/(2*exp(1/2))). - Vaclav Kotesovec, Dec 10 2013
a(n) = n!*abs(Stirling1(2*n+1,n+1))/C(2*n+1,n). - Chai Wah Wu, Jun 08 2025

Extensions

More terms from Max Alekseyev, Dec 02 2013
a(0)=1 prepended by Pontus von Brömssen, Jan 30 2021

A232818 Triangle of coefficients of polynomials equal permanent of the n X n matrix [1,2,...,n; n*x+1, n*x+2, ..., n*x+n; ...; (n-1)*n*x+1, (n-1)*n*x+2, ...,(n-1)*n*x+n].

Original entry on oeis.org

1, 6, 4, 216, 198, 36, 23040, 24640, 7200, 576, 5400000, 6375000, 2362500, 328800, 14400, 2351462400, 2982873600, 1285956000, 238533120, 19051200, 518400, 1707698764800, 2291162509440, 1100516981760, 245735819280, 27025656000, 1383117120, 25401600
Offset: 1

Views

Author

Vladimir Shevelev, Nov 30 2013

Keywords

Comments

The degree of n-th polynomial is n-1.
Its leading coefficient is T(n,1) = n^n*(n-1)!^2*(n+1)/2. - M. F. Hasler, Dec 01 2013

Examples

			                                   1
                           6*x +   4
              216*x^2 +  198*x +  36
23040*x^3 + 24640*x^2 + 7200*x + 576
              ......
		

Crossrefs

Programs

  • Mathematica
    p[n_,x_]:=(-1)^n Sum[n^k x^k StirlingS1[n,n-k]StirlingS1[n+1,k+1](n-k)!k!,{k,0,n-1}];Flatten[Table[Reverse[CoefficientList[p[n,x],x]],{n,8}]] (* Peter J. C. Moses, Nov 30 2013 *)
  • PARI
    P(n)=(-1)^n*sum(k=0,n-1,n^k*x^k*stirling(n,n-k)*stirling(n+1,k+1)*(n-k)!*k!)
    apply(t->Vec(t),vector(7,n,P(n))) /* M. F. Hasler, Dec 01 2013 */

Formula

P_n(x) = (-1)^n * Sum_{k=0..n-1} c_k(n) * x^k, where c_k(n)= n^k * Stirling1(n,n-k) * Stirling1(n+1,k+1) * (n-k)! * k!.
P_n(1) = A232773; P_n(0) = n!^2, P_n(1/n) = A204248(n) is permanent of n X n Toeplitz matrix with the first row n,n-1,...,1 (see our comment in A204248).

Extensions

More terms from Peter J. C. Moses, Nov 30 2013

A381723 a(n) = pos(M(n)), where M(n) is the n X n matrix with numbers 1, 2, ..., n^2 in order across rows, and pos(M(n)) is the positive part of the determinant of M(n); see A380661.

Original entry on oeis.org

1, 4, 225, 27728, 7240350, 3439197360, 2686774125000, 3213645578293248, 5578750547986764960, 13484491722080225280000, 43904082301794970311672000, 187409206411313292409598115840, 1025421491750171253824589270768000, 7056011383804251291488039375527526400
Offset: 1

Views

Author

Clark Kimberling, Mar 09 2025

Keywords

Examples

			M(3) is the matrix with rows (1,2,3), (4,5,6), (7,8,9), determinant 0, permanent 450, negative part -225, and positive part 225.
		

Crossrefs

Programs

  • Mathematica
    r[m_, n_] := Range[(m - 1) n + 1, m  n];
    d = Table[Det[Table[r[m, n], {m, 1, n}]], {n, 1, 15}]
    p = Table[Permanent[Table[r[m, n], {m, 1, n}]], {n, 1, 15}]
    neg = (d - p)/2
    pos = (d + p)/2
  • Python
    from sympy.functions.combinatorial.numbers import stirling, factorial
    def A381723(n): return abs(sum(n**k*stirling(n,n-k,kind=1,signed=True)*stirling(n+1,k+1,kind=1,signed=True)*factorial(n-k)*factorial(k) for k in range(n+1)))>>1 if n>2 else 3*n-2 # Chai Wah Wu, Mar 25 2025

Formula

a(n) = A232773(n)/2 for n >= 3.
Showing 1-5 of 5 results.