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 1-8 of 8 results.

A090221 Array used for numerators of g.f.s for column sequences of array A090214 ((4,4)-Stirling2).

Original entry on oeis.org

1, 96, 72, 14400, 16, 38400, 3456000, 1, 27000, 22104000, 1270080000, 7200, 34905600, 16111872000, 682795008000, 856, 21154176, 48248363520, 15279164006400, 516193026048000, 48, 6064128, 54644474880, 78083415244800
Offset: 4

Views

Author

Wolfdieter Lang, Dec 01 2003

Keywords

Comments

The row length sequence for this array is A037915(k-4)= floor(3*(k-4)/4)+1, k>=4: [1, 1, 2, 3, 4, 4, 5, 6, 7, 7, 8, 9, 10, 10, 11, ...].
The g.f. G(k,x) for the k-th column (with leading zeros) of array A090214 is given there. The recurrence is G(k,x) = x*sum(binomial(k-r,4-r)*fallfac(4,4-r)*G(k-r,x),r=1..4))/(1-fallfac(k,4)*x), k>=4, with inputs G(k,x)=0 for k=1,2,3 and G(4,x)=x/(1-4!*x); where fallfac(n,m) := A008279(n,m) (falling factorials with fallfac(n,0) := 1). Computed from the Blasiak et al. reference, eqs. (20) and (21) with r=4: recurrence for S_{4,4}(n,k).

Examples

			[1]; [96]; [72,14400]; [16,38400,3456000]; [1,27000,22104000,1270080000]; ...
G(5,x)/x^2 = 96/((1-4!*x)*(1-5*4*3*2*x)). kmax(5)=0, hence P(5,x)=a(5,0)=96; x^2 from x^ceiling(5/4).
		

Formula

a(k, n) from: sum(a(k, n)*x^n, n=0..kmax(k)) = G(k, x)* product(1-fallfac(p, 4)*x, p=4..k)/x^ceiling(k/4), k>=4, with G(k, x) defined from the recurrence given above and kmax(k) := A057353(k-4)= floor(3*(k-4)/4)= A037915(k-4)-1.

A090213 Alternating row sums of array A090214 ((4,4)-Stirling2).

Original entry on oeis.org

1, -15, 1169, -154079, -148969375, 778633335441, -4003896394897551, 27901641934428560705, -268555885416357907647039, 3460225909437698652973995569, -56404253763542830420650221273263, 1050004356721541004548911018674177377
Offset: 1

Views

Author

Wolfdieter Lang, Dec 01 2003

Keywords

References

  • P. Blasiak, K. A. Penson and A. I. Solomon, The general boson normal ordering problem, Phys. Lett. A 309 (2003) 198-205.
  • M. Schork, On the combinatorics of normal ordering bosonic operators and deforming it, J. Phys. A 36 (2003) 4651-4665.

Crossrefs

Cf. A000587, A090211-2. A071379 (non-alternating sum, generalized Bell-numbers).

Programs

  • Mathematica
    a[n_] := Sum[(-1)^k FactorialPower[k, 4]^n/k!, {k, 2, Infinity}]*E; Array[a, 12] (* Jean-François Alcover, Sep 01 2016 *)

Formula

a(n) := sum( A090214(n, k)*(-1)^k, k=4..4*n), n>=1. a(0) := 1 may be added.
a(n) = sum(((-1)^k)*(fallfac(k, 4)^n)/k!, k=4..infinity)*exp(1), with fallfac(k, 4)=A008279(k, 4)=k*(k-1)*(k-2)*(k-3) and n>=1. This produces also a(0)=1.
E.g.f. if a(0)=1 is added: exp(1)*(sum(((-1)^k)*exp(fallfac(k, 4)*x)/k!, k=4..infinity) + A000166(3)/3!). with the subfactorials A000166. A000166(3)/3!=1/3. Similar to derivation on top of p. 4656 of the Schork reference.

A091037 Second column (k=5) of array A090214 ((4,4)-Stirling2) divided by 4*4!=96.

Original entry on oeis.org

1, 144, 17856, 2156544, 259117056, 31102009344, 3732432224256, 447896453382144, 53747684481171456, 6449724779548114944, 773967036949154758656, 92876045955579714207744
Offset: 2

Views

Author

Wolfdieter Lang, Jan 23 2004

Keywords

Crossrefs

Cf. A091038 (second column of (5, 5)-Stirling2 array divided by 600).

Formula

a(n)=A090214(n, 5)/(4*4!)= (4!^(n-2))*(5^(n-1)-1)/4, n>=2.
G.f.: (x^2)/((1-5!*x)*(1-4!*x))= (x/(4*4!))*(1/(1-5!*x) - 1/(1-4!*x)).

A091553 Third column (k=6) sequence of array A090214 ((4,4)-Stirling2) divided by 72.

Original entry on oeis.org

1, 704, 300096, 113762304, 41644855296, 15075073327104, 5436979231850496, 1958506906364411904, 705205813266345885696, 253891292037560301256704, 91402929045514567230160896, 32905302125838589613523861504
Offset: 0

Views

Author

Wolfdieter Lang, Feb 13 2004

Keywords

Crossrefs

Cf. A089518 (third column of array (3, 3)-Stirling2 divided by 9).

Formula

a(n)= A090214(n+2, 6)/72, n>=0.
a(n)= (15*(6*5*4*3)^n - 10*(5*4*3*2)^n + (4*3*2*1)^n)/3!.
G.f.: (1+200*x)/product(1-fallfac(p, 4)*x, p=4..6), with fallfac(n, m) := A008279(n, m) (falling factorials).
a(n)= ((4!)^n)*(1-2*5^(n+1)+binomial(6, 2)^(n+1))/3!. From eq.12 of the Blasiak et al. reference given in A078740 with r=4=s, k=6.

A078739 Triangle of generalized Stirling numbers S_{2,2}(n,k) read by rows (n>=1, 2<=k<=2n).

Original entry on oeis.org

1, 2, 4, 1, 4, 32, 38, 12, 1, 8, 208, 652, 576, 188, 24, 1, 16, 1280, 9080, 16944, 12052, 3840, 580, 40, 1, 32, 7744, 116656, 412800, 540080, 322848, 98292, 16000, 1390, 60, 1, 64, 46592, 1446368, 9196992, 20447056, 20453376, 10564304, 3047520, 511392, 50400
Offset: 1

Views

Author

N. J. A. Sloane, Dec 21 2002

Keywords

Comments

A generalization of the Stirling2 numbers S_{1,1} from A008277.
The g.f. for column k=2*K is (x^K)*pe(K,x)*d(k,x) and for k=2*K+1 it is (x^K)*po(K,x)*2*(K+1)*K*d(k,x), K>= 1, with d(k,x) := 1/product(1-p*(p-1)*x,p=2..k) and the row polynomials pe(n,x) := sum(A089275(n,m)*x^m,m=0..n-1) and po(n,x) := sum(A089276(n,m)*x^m,m=0..n-1). - Wolfdieter Lang, Nov 07 2003
The formula for the k-th column sequence is given in A089511.
Codara et al., show that T(n,k) gives the number of k-colorings of the graph nK_2 (the disjoint union of n copies of the complete graph K_2). An example is given below. - Peter Bala, Aug 15 2013

Examples

			From _Peter Bala_, Aug 15 2013: (Start)
The table begins
n\k | 2    3    4    5    6   7   8
= = = = = = = = = = = = = = = = = =
  1 | 1
  2 | 2    4    1
  3 | 4   32   38   12    1
  4 | 8  208  652  576  188  24   1
...
Graph coloring interpretation of T(2,3) = 4: The graph 2K_2 is 2 copies of K_2, the complete graph on 2 vertices:
o---o  o---o
a   b  c   d
The four 3-colorings of 2K_2 are ac|b|d, ad|b|c, bc|a|d and bd|a|c. (End)
		

Crossrefs

Row sums give A020556. Triangle S_{1, 1} = A008277, S_{2, 1} = A008297 (ignoring signs), S_{3, 1} = A035342, S_{3, 2} = A078740, S_{3, 3} = A078741. A090214 (S_{4,4}).
The column sequences are A000079(n-1)(powers of 2), 4*A016129(n-2), A089271, 12*A089272, A089273, etc.
Main diagonal is A217900.
Cf. A071951 (Legendre-Stirling triangle).

Programs

  • Maple
    # Note that the function implements the full triangle because it can be
    # much better reused and referenced in this form.
    A078739 := proc(n,k) local r;
    add((-1)^(n-r)*binomial(n,r)*combinat[stirling2](n+r,k),r=0..n) end:
    # Displays the truncated triangle from the definition:
    seq(print(seq(A078739(n,k),k=2..2*n)),n=1..6); # Peter Luschny, Mar 25 2011
  • Mathematica
    t[n_, k_] := Sum[(-1)^(n-r)*Binomial[n, r]*StirlingS2[n+r, k], {r, 0, n}]; Table[t[n, k], {n, 1, 7}, {k, 2, 2*n}] // Flatten (* Jean-François Alcover, Apr 11 2013, after Peter Luschny *)

Formula

a(n, k) = sum(binomial(k-2+p, p)*A008279(2, p)*a(n-1, k-2+p), p=0..2) if 2 <= k <= 2*n for n>=1, a(1, 2)=1; else 0. Here A008279(2, p) gives the third row (k=2) of the augmented falling factorial triangle: [1, 2, 2] for p=0, 1, 2. From eq.(21) with r=2 of the Blasiak et al. paper.
a(n, k) = (((-1)^k)/k!)*sum(((-1)^p)*binomial(k, p)*A008279(p, 2)^n, p=2..k) for 2 <= k <= 2*n, n>=1. From eq.(19) with r=2 of the Blasiak et al. paper.
a(n, k) = sum(A071951(n, j)*A089503(j, 2*j-k+1), j=ceiling(k/2)..min(n, k-1)), 1<=n, 2<=k<=2n; relation to Legendre-Stirling triangle. Wolfdieter Lang, Dec 01 2003
a(n, k) = A122193(n,k)*2^n/k! - Peter Luschny, Mar 25 2011
E^n = sum_{k=2}^(2n) a(n,k)*x^k*D^k where D is the operator d/dx, and E the operator x^2d^2/dx^2.
The row polynomials R(n,x) are given by the Dobinski-type formula R(n,x) = exp(-x)*sum {k = 0..inf} (k*(k-1))^n*x^k/k!. - Peter Bala, Aug 15 2013

Extensions

More terms from Wolfdieter Lang, Nov 07 2003

A078741 Triangle of generalized Stirling numbers S_{3,3}(n,k) read by rows (n>=1, 3<=k<=3n).

Original entry on oeis.org

1, 6, 18, 9, 1, 36, 540, 1242, 882, 243, 27, 1, 216, 13608, 94284, 186876, 149580, 56808, 11025, 1107, 54, 1, 1296, 330480, 6148872, 28245672, 49658508, 41392620, 18428400, 4691412, 706833, 63375, 3285, 90, 1, 7776, 7954848, 380841264, 3762380016, 13062960720
Offset: 1

Views

Author

N. J. A. Sloane, Dec 21 2002

Keywords

Comments

The sequence of row lengths for this array is [1,4,7,10,..]= A016777(n-1), n>=1.
The g.f. for the k-th column, (with leading zeros and k>=3) is G(k,x)= x^ceiling(k/3)*P(k,x)/product(1-fallfac(p,3)*x,p=3..k), with fallfac(n,m) := A008279(n,m) (falling factorials) and P(k,x) := sum(A089517(k,m)*x^m,m=0..kmax(k)), k>=3, with kmax(k) := A004523(k-3)= floor(2*(k-3)/3)= [0,0,1,2,2,3,4,4,5,...]. For the recurrence of the G(k,x) see A089517. Wolfdieter Lang, Dec 01 2003
For the computation of the k-th column sequence see A090219.
Codara et al., show that T(n,k) gives the number of k-colorings of the graph nK_3 (the disjoint union of n copies of the complete graph K_3). An example is given below. - Peter Bala, Aug 15 2013

Examples

			From _Peter Bala_, Aug 15 2013: (Start)
The table begins
n\k |   3     4     5      6      7     8     9   10  11  12
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  1 |   1
  2 |   6    18     9      1
  3 |  36   540  1242    882    243    27     1
  4 | 216 13608 94284 186876 149580 56808 11025 1107  54   1
...
Graph coloring interpretation of T(2,3) = 6:
The graph 2K_3 is 2 copies of K_3, the complete graph on 3 vertices:
    o b      o e
   / \      / \
  o---o    o---o
  a   c    d   f
The six 3-colorings of 2K_3 are ad|be|cf, ad|bf|ce, ae|bd|cf, ae|bf|cd, af|bd|ce, and af|be|cd. (End)
		

Crossrefs

Row sums give A069223. Cf. A078739.
The column sequences (without leading zeros) are A000400 (powers of 6), 18*A089507, 9*A089518, A089519, etc.
A089504, A069223 (row sums), A090212 (alternating row sums).

Programs

  • Mathematica
    a[n_, k_] := (-1)^k*Sum[(-1)^p*((p-2)*(p-1)*p)^n*Binomial[k, p], {p, 3, k}]/k!; Table[a[n, k], {n, 1, 6}, {k, 3, 3*n}] // Flatten (* Jean-François Alcover, Dec 04 2013 *)

Formula

a(n, k) = (((-1)^k)/k!)*Sum_{p = 3..k} (-1)^p* binomial(k, p)*fallfac(p, 3)^n, with fallfac(p, 3) := A008279(p, 3) = p*(p-1)*(p-2); 3 <= k <= 3*n, n >= 1, else 0. From eq.(19) with r = 3 of the Blasiak et al. reference.
E^n = Sum_{k = 3..3*n} a(n,k)*x^k*D^k where D is the operator d/dx, and E the operator x^3d^3/dx^3.
The row polynomials R(n,x) are given by the Dobinski-type formula R(n,x) = exp(-x)*Sum_{k >= 0} (k*(k-1)*(k-2))^n*x^k/k!. - Peter Bala, Aug 15 2013

A090215 A generalization of triangles A071951 (Legendre-Stirling) and A089504.

Original entry on oeis.org

1, 24, 1, 576, 144, 1, 13824, 17856, 504, 1, 331776, 2156544, 199296, 1344, 1, 7962624, 259117056, 73903104, 1328256, 3024, 1, 191102976, 31102009344, 26864234496, 1189638144, 6408576, 6048, 1, 4586471424, 3732432224256, 9702226427904, 1026160275456, 11956045824, 24697728, 11088, 1
Offset: 1

Views

Author

Wolfdieter Lang, Dec 01 2003

Keywords

Comments

This triangle underlies the array entry A090214 ((4,4)-generalized Stirling2).

Examples

			[1]; [24,1]; [576,144,1]; [13824,17856,504,1]; ...
		

Crossrefs

Cf. A071951 (Legendre-Stirling, (2, 2) case), A089504 ((3, 3)-case).
The column sequences (without leading zeros) are A009968 (powers of 24), etc.

Programs

  • Mathematica
    max = 10; f[m_] := 1/Product[1-FactorialPower[r+3, 4]*x, {r, 1, m}]; col[m_] := CoefficientList[f[m] + O[x]^(max-m+1), x]; a[n_, m_] := col[m][[n-m+1]]; Table[a[n, m], {n, 1, max}, {m, 1, n}] // Flatten (* Jean-François Alcover, Sep 01 2016 *)

Formula

G.f. for m-th column sequence (without leading zeros and m>=1) is 1/product(1-fallfac(r+3, 4)*x, r=1..m) with fallfac(n, k) := A008279(n, k) (falling factorials).
a(n, m) = sum(A089515(m, p)*fallfac(p, 4)^(n-m), p=1..m)/D(m) if n>=m>=1 else 0; with D(m) := A089516(m).

Extensions

More terms coming from a-file added by Michel Marcus, Feb 08 2023

A216379 Triangle of generalized Stirling numbers S_{n,n}(5,k) read by rows (n>=0, n<=k<=5n) the sum of which is A182924.

Original entry on oeis.org

1, 1, 15, 25, 10, 1, 16, 1280, 9080, 16944, 12052, 3840, 580, 40, 1, 1296, 330480, 6148872, 28245672, 49658508, 41392620, 18428400, 4691412, 706833, 63375, 3285, 90, 1, 331776, 207028224, 8190885888, 74684104704, 253100173824, 405044582400, 351783415296, 181005401088, 58436640576, 12288192000, 1721191680, 162115584, 10228144, 423360, 10960, 160, 1
Offset: 0

Views

Author

Jean-François Alcover, Sep 06 2012

Keywords

Examples

			{1},
{1,15,25,10,1},
{16,1280,9080,16944,12052,3840,580,40,1}
...
		

Crossrefs

Cf. A182924.
Second row (n=1) is 5th row of A008277 (Stirling numbers S2).
Third row is 5th row of A078739 (Generalized Stirling numbers S_{2,2}).
Fourth row is 5th row of A078741 (Generalized Stirling numbers S_{3,3}).
Fifth row is 5th row of A090214 (Generalized Stirling numbers S_{4,4}).

Programs

  • Mathematica
    f[m_][n_, k_] := (-1)^k/k!*Sum[(-1)^p*Binomial[k, p]*FactorialPower[p, m]^n, {p, m, k}]; Table[f[n][5, k],{n,0,4}, {k, n, 5*n}]//Flatten
Showing 1-8 of 8 results.