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 1-4 of 4 results.

A090210 Triangle of certain generalized Bell numbers.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 5, 7, 1, 1, 15, 87, 34, 1, 1, 52, 1657, 2971, 209, 1, 1, 203, 43833, 513559, 163121, 1546, 1, 1, 877, 1515903, 149670844, 326922081, 12962661, 13327, 1, 1, 4140, 65766991, 66653198353, 1346634725665, 363303011071, 1395857215, 130922, 1, 1
Offset: 1

Views

Author

Wolfdieter Lang, Dec 01 2003

Keywords

Comments

Let B_{n}(x) = sum_{j>=0}(exp(j!/(j-n)!*x-1)/j!) and
S(n,k) = k! [x^k] taylor(B_{n}(x)), where [x^k] denotes the
coefficient of x^k in the Taylor series for B_{n}(x).
Then S(n,k) (n>0, k>=0) is the square array representation of the triangle.
To illustrate the cross-references of T(n,k) when written as a square array.
0: A000012: 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1: A000110: 1, 1, 2, 5, 15, 52, 203, 877, 4140, ...
2: A020556: 1, 1, 7, 87, 1657, 43833, 1515903, ...
3: A069223: 1, 1, 34, 2971, 513559, 149670844, ...
4: A071379: 1, 1, 209, 163121, 326922081, ...
5: A090209: 1, 1, 1546, 12962661, 363303011071,...
6: ... 1, 1, 13327, 1395857215, 637056434385865,...
Note that the sequence T(0,k) is not included in the data.
- Peter Luschny, Mar 27 2011

Examples

			Triangle begins:
1;
1, 1;
2, 1, 1;
5, 7, 1, 1;
15, 87, 34, 1, 1;
52, 1657, 2971, 209, 1, 1;
203, 43833, 513559, 163121, 1546, 1, 1;
		

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

Programs

  • Maple
    A090210_AsSquareArray := proc(n,k) local r,s,i;
    if k=0 then 1 else r := [seq(n+1,i=1..k-1)]; s := [seq(1,i=1..k-1)];
    exp(-x)*n!^(k-1)*hypergeom(r,s,x); round(evalf(subs(x=1,%),99)) fi end:
    seq(lprint(seq(A090210_AsSquareArray(n,k),k=0..6)),n=0..6);
    # Peter Luschny, Mar 30 2011
  • Mathematica
    t[n_, k_] := t[n, k] = Sum[(n+j)!^(k-1)/(j!^k*E), {j, 0, Infinity}]; t[_, 0] = 1;
    Flatten[ Table[ t[n-k+1, k], {n, 0, 8}, {k, n, 0, -1}]][[1 ;; 43]] (* Jean-François Alcover, Jun 17 2011 *)

Formula

a(n, m) = Bell(m;n-(m-1)), n>= m-1 >=0, with Bell(m;k) := Sum_{p=m..m*k} S2(m;k, p), where S2(m;k, p) := (((-1)^p)/p!) * Sum_{r=m..p} ((-1)^r)*binomial(p, r)*fallfac(r, m)^k; with fallfac(n, m) := A008279(n, m) (falling factorials) and m<=p<=k*m, k>=1, m=1, 2, ..., else 0. From eqs.(6) with r=s->m and eq.(19) with S_{r, r}(n, k)-> S2(r;n, k) of the Blasiak et al. reference. [Corrected by Sean A. Irvine, Jun 03 2024]
a(n, m) = (Sum_{k>=m} fallfac(k, m)^(n-(m-1)))/exp(1), n>=m-1>=0, else 0. From eq.(26) with r->m of the Schork reference which is rewritten eq.(11) of the original Blasiak et al. reference.
E.g.f. m-th column (no leading zeros): (Sum_{k>=m} exp(fallfac(k, m)*x)/k!) + A000522(m)/m!)/exp(1). Rewritten from the top of p. 4656 of the Schork reference.

A090216 Generalized Stirling2 array S_{5,5}(n,k).

Original entry on oeis.org

1, 120, 600, 600, 200, 25, 1, 14400, 504000, 2664000, 4608000, 3501000, 1350360, 284800, 33800, 2225, 75, 1, 1728000, 371520000, 7629120000, 42762240000, 97388280000, 110386900800, 70137648000, 26920728000, 6548346000, 1039382000
Offset: 1

Views

Author

Wolfdieter Lang, Dec 01 2003

Keywords

Comments

The row length sequence for this array is [1, 6, 11, 16, 21, 26, 31,...]= A016861(n-1), n>=1.
The g.f. for the k-th column, (with leading zeros and k>=5) is G(k,x)= x^ceiling(k/5)*P(k,x)/product(1-fallfac(p,5)*x,p=5..k), with fallfac(n,m) := A008279(n,m) (falling factorials) and P(k,x) := sum(A090222(k,m)*x^m,m=0..kmax(k)), k>=5, with kmax(k) := floor(4*(k-5)/5)= A090223(k-5). For the recurrence of the G(k,x) see A090222.

Examples

			Triangle begins:
  [1];
  [120,600,600,200,25,1];
  [14400,504000,2664000,4608000,3501000,1350360,284800,33800,2225,75,1];
  ...
		

Crossrefs

Cf. A090217, A090209 (row sums), A090218 (alternating row sums).

Programs

  • Mathematica
    fallfac[n_, k_] := Pochhammer[n-k+1, k]; a[n_, k_] := (((-1)^k)/k!)*Sum[((-1)^p)*Binomial[k, p]*fallfac[p, 5]^n, {p, 5, k}]; Table[a[n, k], {n, 1, 5}, {k, 5, 5*n}] // Flatten (* Jean-François Alcover, Mar 05 2014 *)
  • Python
    from sympy import binomial, factorial, ff
    def a(n, k): return sum((-1)**p * binomial(k, p) * ff(p, 5)**n for p in range(5, k+1)) * (-1)**k / factorial(k) # David Radcliffe, Jul 01 2025

Formula

a(n, k) = (((-1)^k)/k!)*sum(((-1)^p)*binomial(k, p)*fallfac(p, 5)^n, p=5..k), with fallfac(p, 5) := A008279(p, 5)=product(p+1-q, q=1..5); 5<= k <= 5*n, n>=1, else 0. From eq.(19) with r=5 of the Blasiak et al. reference.
E^n = Sum_{k=5..5n) a(n,k)*x^k*D^k where D is the operator d/dx, and E the operator x^5d^5/dx^5.

A182933 Generalized Bell numbers based on the rising factorial powers; square array read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 5, 27, 13, 1, 1, 15, 409, 778, 73, 1, 1, 52, 9089, 104149, 37553, 501, 1, 1, 203, 272947, 25053583, 57184313, 2688546, 4051, 1, 1, 877, 10515147, 9566642254, 192052025697, 56410245661, 265141267, 37633, 1
Offset: 0

Views

Author

Peter Luschny, Mar 29 2011

Keywords

Comments

These numbers are related to the generalized Bell numbers based on the falling factorial powers (A090210).
The square array starts for n>=0, k>=0:
n\k=0,1,.. A000012,A000262,A182934,...
0: A000012: 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...
1: A000110: 1, 1, 2, 5, 15, 52, 203, 877, 4140, ...
2: A094577: 1, 3, 27, 409, 9089, 272947, 10515147, ...
3: A182932: 1, 13, 778, 104149, 25053583, 9566642254, ...
4: : 1, 73, 37553, 57184313, 192052025697, ...
5: : 1, 501, 2688546, 56410245661, ...
6: .... : 1, 4051, 265141267, 89501806774945, ...

Crossrefs

Programs

  • Maple
    A182933_AsSquareArray := proc(n,k) local r,s,i;
    r := [seq(n+1,i=1..k)]; s := [seq(1,i=1..k-1),2];
    exp(-x)*n!^k*hypergeom(r,s,x); round(evalf(subs(x=1,%),99)) end:
    seq(lprint(seq(A182933_AsSquareArray(n,k),k=0..6)),n=0..6);
  • Mathematica
    a[n_, k_] := Exp[-1]*n!^k*HypergeometricPFQ[ Table[n+1, {k}], Append[ Table[1, {k-1}], 2], 1.]; Table[ a[n-k, k] // Round , {n, 0, 8}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Jul 29 2013 *)

Formula

Let r_k = [n+1,...,n+1] (k occurrences of n+1), s_k = [1,...,1,2] (k-1 occurrences of 1) and F_k the generalized hypergeometric function of type k_F_k, then a(n,k) = exp(-1)*n!^k*F_k(r_k, s_k | 1).
Let B_{n}(x) = sum_{j>=0}(exp((j+n-1)!/(j-1)!*x-1)/j!) then a(n,k) = k! [x^k] series(B_{n}(x)), where [x^k] denotes the coefficient of x^k in the Taylor series for B_{n}(x).

A283154 Number of set partitions of unique elements from an n X 5 matrix where elements from the same row may not be in the same partition.

Original entry on oeis.org

1, 1546, 12962661, 363303011071, 25571928251231076, 3789505947767235111051, 1049433111253356296672432821, 498382374325731085522315594481036, 380385281554629647028734545622539438171, 443499171330317702437047276255605780991365151, 758311423589226886694849718263394302618332719358226
Offset: 1

Views

Author

Marko Riedel, Mar 01 2017

Keywords

Comments

Apparently a duplicate of A090209. - R. J. Mathar, Mar 06 2017

Crossrefs

Programs

  • Mathematica
    Table[(5 !^n)*Sum[Binomial[p,5]^n/p ! * Sum[(-1)^k/k !,{k,0,5n-p}],{p,1,5n}],{n,1,11}] (* Indranil Ghosh, Mar 04 2017 *)
  • PARI
    a(n) = (5!^n)*sum(p=1,5*n,binomial(p,5)^n/p! * sum(k=0,5*n-p,(-1)^k/k!)); \\ Indranil Ghosh, Mar 04 2017

Formula

a(n) = m!^n Sum_{p=1..n*m} (Choose(p,m)^n/p!) Sum_{k=0..n*m-p} (-1)^k/k! with m=5.

Extensions

If it is proved that A283154 and A090209 are the same, then the entries should be merged and A283154 recycled. - N. J. A. Sloane, Mar 06 2017
Showing 1-4 of 4 results.