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 1-3 of 3 results.

A094418 Generalized ordered Bell numbers Bo(5,n).

Original entry on oeis.org

1, 5, 55, 905, 19855, 544505, 17919055, 687978905, 30187495855, 1490155456505, 81732269223055, 4931150091426905, 324557348772511855, 23141780973332248505, 1776997406800302687055, 146197529083891406394905, 12829862285488250150167855, 1196280147496701351115120505
Offset: 0

Views

Author

Ralf Stephan, May 02 2004

Keywords

Comments

Fifth row of array A094416, which has more information.

Crossrefs

Programs

  • Magma
    A094416:= func< n,k | (&+[Factorial(j)*n^j*StirlingSecond(k,j): j in [0..k]]) >;
    A094418:= func< k | A094416(5,k) >;
    [A094418(n): n in [0..30]]; // G. C. Greubel, Jan 12 2024
    
  • Mathematica
    t = 30; Range[0, t]! CoefficientList[Series[1/(6 - 5 Exp[x]), {x, 0, t}], x] (* Vincenzo Librandi, Mar 16 2014 *)
  • PARI
    my(N=25,x='x+O('x^N)); Vec(serlaplace(1/(6 - 5*exp(x)))) \\ Joerg Arndt, Jan 15 2024
  • SageMath
    def A094416(n,k): return sum(factorial(j)*n^j*stirling_number2(k,j) for j in range(k+1)) # array
    def A094418(k): return A094416(5,k)
    [A094418(n) for n in range(31)] # G. C. Greubel, Jan 12 2024
    

Formula

E.g.f.: 1/(6 - 5*exp(x)).
a(n) = Sum_{k=0..n} A131689(n,k) * 5^k. - Philippe Deléham, Nov 03 2008
a(n) ~ n! / (6*(log(6/5))^(n+1)). - Vaclav Kotesovec, Mar 14 2014
a(0) = 1; a(n) = 5 * Sum_{k=1..n} binomial(n,k) * a(n-k). - Ilya Gutkovskiy, Jan 17 2020
a(0) = 1; a(n) = 5 * a(n-1) - 6 * Sum_{k=1..n-1} (-1)^k * binomial(n-1,k) * a(n-k). - Seiichi Manyama, Nov 16 2023
From Seiichi Manyama, Jun 01 2025: (Start)
a(n) = (-1)^(n+1)/6 * Li_{-n}(6/5), where Li_{n}(x) is the polylogarithm function.
a(n) = (1/6) * Sum_{k>=0} k^n * (5/6)^k.
a(n) = (5/6) * Sum_{k=0..n} 6^k * (-1)^(n-k) * A131689(n,k) for n > 0. (End)

A094416 Array read by antidiagonals: generalized ordered Bell numbers Bo(r,n).

Original entry on oeis.org

1, 2, 3, 3, 10, 13, 4, 21, 74, 75, 5, 36, 219, 730, 541, 6, 55, 484, 3045, 9002, 4683, 7, 78, 905, 8676, 52923, 133210, 47293, 8, 105, 1518, 19855, 194404, 1103781, 2299754, 545835, 9, 136, 2359, 39390, 544505, 5227236, 26857659, 45375130, 7087261
Offset: 1

Views

Author

Ralf Stephan, May 02 2004

Keywords

Comments

Also, r times the number of (r+1)-level labeled linear rooted trees with n leaves.
"AIJ" (ordered, indistinct, labeled) transform of {r,r,r,...}.
Stirling transform of r^n*n!, i.e. of e.g.f. 1/(1-r*x).
Also, Bo(r,s) is ((x*d/dx)^n)(1/(1+r-r*x)) evaluated at x=1.
r-th ordered Bell polynomial (A019538) evaluated at n.
Bo(r,n) is the n-th moment of a geometric distribution with probability parameter = 1/(r+1). Here, geometric distribution is the number of failures prior to the first success. - Geoffrey Critzer, Jan 01 2019
Row r (starting at r=0), Bo(r+1, n), is the Akiyama-Tanigawa algorithm applied to the powers of r+1. See Python program below. - Shel Kaphan, May 03 2024

Examples

			Array begins as:
  1,  3,   13,    75,     541,     4683,      47293, ...
  2, 10,   74,   730,    9002,   133210,    2299754, ...
  3, 21,  219,  3045,   52923,  1103781,   26857659, ...
  4, 36,  484,  8676,  194404,  5227236,  163978084, ...
  5, 55,  905, 19855,  544505, 17919055,  687978905, ...
  6, 78, 1518, 39390, 1277646, 49729758, 2258233998, ...
		

Crossrefs

Columns include A014105, A094421.
Main diagonal is A094420.
Antidiagonal sums are A094422.

Programs

  • Magma
    A094416:= func< n,k | (&+[Factorial(j)*n^j*StirlingSecond(k,j): j in [0..k]]) >;
    [A094416(n-k+1,k): k in [1..n], n in [1..12]]; // G. C. Greubel, Jan 12 2024
    
  • Mathematica
    Bo[, 0]=1; Bo[r, n_]:= Bo[r, n]= r*Sum[Binomial[n,k] Bo[r,n-k], {k, n}];
    Table[Bo[r-n+1, n], {r, 10}, {n, r}] // Flatten (* Jean-François Alcover, Nov 03 2018 *)
  • Python
    # The Akiyama-Tanigawa algorithm applied to the powers of r + 1
    # generates the rows. Adds one row (r=0) and one column (n=0).
    # Adapted from Peter Luschny on A371568.
    def f(n, r): return (r + 1)**n
    def ATtransform(r, len, f):
      A = [0] * len
      R = [0] * len
      for n in range(len):
          R[n] = f(n, r)
          for j in range(n, 0, -1):
              R[j - 1] = j * (R[j] - R[j - 1])
          A[n] = R[0]
      return A
    for r in range(8): print([r], ATtransform(r, 8, f)) # Shel Kaphan, May 03 2024
  • SageMath
    def A094416(n,k): return sum(factorial(j)*n^j*stirling_number2(k,j) for j in range(k+1)) # array
    flatten([[A094416(n-k+1,k) for k in range(1,n+1)] for n in range(1,13)]) # G. C. Greubel, Jan 12 2024
    

Formula

E.g.f.: 1/(1 + r*(1 - exp(x))).
Bo(r, n) = Sum_{k=0..n} k!*r^k*Stirling2(n, k) = 1/(r+1) * Sum_{k>=1} k^n * (r/(r+1))^k, for r>0, n>0.
Recurrence: Bo(r, n) = r * Sum_{k=1..n} C(n, k)*Bo(r, n-k), with Bo(r, 0) = 1.
Bo(r,0) = 1, Bo(r,n) = r*Bo(r,n-1) - (r+1)*Sum_{j=1..n-1} (-1)^j * binomial(n-1,j) * Bo(r,n-j). - Seiichi Manyama, Nov 17 2023

Extensions

Offset corrected by Geoffrey Critzer, Jan 01 2019

A372346 a(n) = Sum_{j=0..n} p(n - j, j) where p(n, x) = Sum_{k=0..n} k! * Stirling2(n, k) * x^k. Row sums of A344499.

Original entry on oeis.org

1, 1, 2, 6, 27, 175, 1532, 17276, 243093, 4165261, 85133686, 2039546786, 56447550543, 1783865468187, 63766726231792, 2558290237404920, 114418196763735113, 5670168958036693977, 309630356618418661738, 18536683645526372648446, 1211038603734731649106307, 85983731724631359047504967
Offset: 0

Views

Author

Peter Luschny, Apr 28 2024

Keywords

Crossrefs

Programs

  • Maple
    p := n -> local k; add(k!*Stirling2(n, k)*x^k, k = 0..n):
    a := n -> local j; add(subs(x = j, p(n - j)),  j = 0..n):
    seq(a(n), n = 0..21);

Formula

a(n) = A094422(n - 1) + 1.
Showing 1-3 of 3 results.