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.

A293037 E.g.f.: exp(1 + x - exp(x)).

Original entry on oeis.org

1, 0, -1, -1, 2, 9, 9, -50, -267, -413, 2180, 17731, 50533, -110176, -1966797, -9938669, -8638718, 278475061, 2540956509, 9816860358, -27172288399, -725503033401, -5592543175252, -15823587507881, 168392610536153, 2848115497132448, 20819319685262839
Offset: 0

Views

Author

Seiichi Manyama, Sep 28 2017

Keywords

Crossrefs

Column k=1 of A293051.
Column k=1 of A335977.
Cf. A000587 (k=0), this sequence (k=1), A293038 (k=2), A293039 (k=3), A293040 (k=4).

Programs

  • Maple
    f:= series(exp(1 + x - exp(x)), x= 0, 101): seq(factorial(n) * coeff(f, x, n), n = 0..30); # Muniru A Asiru, Oct 31 2017
    # second Maple program:
    b:= proc(n, t) option remember; `if`(n=0, 1-2*t,
          add(b(n-j, 1-t)*binomial(n-1, j-1), j=1..n))
        end:
    a:= n-> b(n+1, 1):
    seq(a(n), n=0..35);  # Alois P. Heinz, Dec 01 2021
  • Mathematica
    m = 26; Range[0, m]! * CoefficientList[Series[Exp[1 + x - Exp[x]], {x, 0, m}], x] (* Amiram Eldar, Jul 06 2020 *)
    Table[Sum[Binomial[n, k] * BellB[k, -1], {k, 0, n}], {n, 0, 30}] (* Vaclav Kotesovec, Jul 06 2020 *)
  • PARI
    my(N=40, x='x+O('x^N)); Vec(serlaplace(exp(-exp(x)+1+x)))
    
  • PARI
    a(n) = if(n==0, 1, -sum(k=0, n-2, binomial(n-1, k)*a(k))); \\ Seiichi Manyama, Aug 02 2021

Formula

a(n) = exp(1) * Sum_{k>=0} (-1)^k*(k + 1)^n/k!. - Ilya Gutkovskiy, Jun 13 2019
a(n) = Sum_{k=0..n} binomial(n,k) * Bell(k, -1). - Vaclav Kotesovec, Jul 06 2020
a(0) = 1; a(n) = - Sum_{k=0..n-2} binomial(n-1,k) * a(k). - Seiichi Manyama, Aug 02 2021

A293024 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of e.g.f. exp(exp(x) - Sum_{i=0..k} x^i/i!).

Original entry on oeis.org

1, 1, 1, 1, 0, 2, 1, 0, 1, 5, 1, 0, 0, 1, 15, 1, 0, 0, 1, 4, 52, 1, 0, 0, 0, 1, 11, 203, 1, 0, 0, 0, 1, 1, 41, 877, 1, 0, 0, 0, 0, 1, 11, 162, 4140, 1, 0, 0, 0, 0, 1, 1, 36, 715, 21147, 1, 0, 0, 0, 0, 0, 1, 1, 92, 3425, 115975, 1, 0, 0, 0, 0, 0, 1, 1, 36, 491, 17722, 678570
Offset: 0

Views

Author

Seiichi Manyama, Sep 28 2017

Keywords

Comments

A(n,k) is the number of set partitions of [n] into blocks of size > k.

Examples

			Square array begins:
    1,   1,  1, 1, 1, 1, 1, 1, ...
    1,   0,  0, 0, 0, 0, 0, 0, ...
    2,   1,  0, 0, 0, 0, 0, 0, ...
    5,   1,  1, 0, 0, 0, 0, 0, ...
   15,   4,  1, 1, 0, 0, 0, 0, ...
   52,  11,  1, 1, 1, 0, 0, 0, ...
  203,  41, 11, 1, 1, 1, 0, 0, ...
  877, 162, 36, 1, 1, 1, 1, 0, ...
		

Crossrefs

Columns k=0..5 give A000110, A000296, A006505, A057837, A057814, A293025.
Rows n=0..1 give A000012, A000007.
Main diagonal gives A000007.
Cf. A182931, A282988 (as triangle), A293051, A293053.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(n=0, 1, add(
          A(n-j, k)*binomial(n-1, j-1), j=1+k..n))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..14);  # Alois P. Heinz, Sep 28 2017
  • Mathematica
    A[0, _] = 1;
    A[n_, k_] /; 0 <= k <= n := A[n, k] = Sum[A[n-j, k] Binomial[n-1, j-1], {j, k+1, n}];
    A[, ] = 0;
    Table[A[n-k, k], {n, 0, 11}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 06 2019 *)
  • Ruby
    def ncr(n, r)
      return 1 if r == 0
      (n - r + 1..n).inject(:*) / (1..r).inject(:*)
    end
    def A(k, n)
      ary = [1]
      (1..n).each{|i| ary << (k..i - 1).inject(0){|s, j| s + ncr(i - 1, j) * ary[-1 - j]}}
      ary
    end
    def A293024(n)
      a = []
      (0..n).each{|i| a << A(i, n - i)}
      ary = []
      (0..n).each{|i|
        (0..i).each{|j|
          ary << a[i - j][j]
        }
      }
      ary
    end
    p A293024(20)

Formula

E.g.f. of column k: Product_{i>k} exp(x^i/i!).
A(0,k) = 1, A(1,k) = A(2,k) = ... = A(k,k) = 0 and A(n,k) = Sum_{i=k..n-1} binomial(n-1,i)*A(n-1-i,k) for n > k.

A293038 E.g.f.: exp(1 + x + x^2/2! - exp(x)).

Original entry on oeis.org

1, 0, 0, -1, -1, -1, 9, 34, 90, -71, -1645, -9439, -25367, 45902, 1070146, 7122361, 24063637, -54352333, -1501032375, -12319959348, -53177369044, 80189626539, 3910291080509, 40317032441401, 228707685648269, 38882013140648, -16392939262378536
Offset: 0

Views

Author

Seiichi Manyama, Sep 28 2017

Keywords

Crossrefs

Column k=2 of A293051.
Cf. A000587 (k=0), A293037 (k=1), this sequence (k=2), A293039 (k=3), A293040 (k=4).
Cf. A006505.

Programs

  • Maple
    seq(factorial(n) * coeftayl(exp(1+x+x^2/2!-exp(x)), x = 0, n),n = 0..50); # Muniru A Asiru, Oct 05 2017
  • PARI
    my(x='x+O('x^66)); Vec(serlaplace(exp(-exp(x)+1+x+x^2/2)))

Formula

a(0) = 1; a(n) = -Sum_{k=3..n} binomial(n-1,k-1) * a(n-k). - Ilya Gutkovskiy, Nov 20 2020

A293039 E.g.f.: exp(1 + x + x^2/2! + x^3/3! - exp(x)).

Original entry on oeis.org

1, 0, 0, 0, -1, -1, -1, -1, 34, 125, 335, 791, -4027, -41328, -223510, -966174, -1082043, 22493107, 255137121, 1853859145, 8611832136, 6734302429, -364364045001, -4974309134233, -41550393316275, -223452696895652, -173393115915136, 14282249293678744
Offset: 0

Views

Author

Seiichi Manyama, Sep 28 2017

Keywords

Crossrefs

Column k=3 of A293051.
Cf. A000587 (k=0), A293037 (k=1), A293038 (k=2), this sequence (k=3), A293040 (k=4).
Cf. A057837.

Programs

  • Mathematica
    With[{nn=30},CoefficientList[Series[Exp[1+x+x^2/2!+x^3/3!-Exp[x]],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Oct 19 2022 *)
  • PARI
    my(x='x+O('x^66)); Vec(serlaplace(exp(-exp(x)+1+x+x^2/2+x^3/6)))

Formula

a(0) = 1; a(n) = -Sum_{k=4..n} binomial(n-1,k-1) * a(n-k). - Ilya Gutkovskiy, Nov 20 2020

A293040 E.g.f.: exp(1 + x + x^2/2! + x^3/3! + x^4/4! - exp(x)).

Original entry on oeis.org

1, 0, 0, 0, 0, -1, -1, -1, -1, -1, 125, 461, 1253, 3002, 6720, -111684, -978758, -5246983, -22948029, -89534309, 164027151, 5722510249, 55413784239, 393256686307, 2377996545081, 7807749195198, -46231762188586, -1125536160278906, -12849721017510166
Offset: 0

Views

Author

Seiichi Manyama, Sep 28 2017

Keywords

Crossrefs

Column k=4 of A293051.
Cf. A000587 (k=0), A293037 (k=1), A293038 (k=2), A293039 (k=3), this sequence (k=4).
Cf. A057814.

Programs

  • Maple
    seq(factorial(n)*coeftayl(exp(1+x+x^2/2!+x^3/3!+x^4/4!-exp(x)), x = 0, n),n=0..50); # Muniru A Asiru, Oct 06 2017
  • PARI
    my(x='x+O('x^66)); Vec(serlaplace(exp(-exp(x)+1+x+x^2/2+x^3/6+x^4/24)))

Formula

a(0) = 1; a(n) = -Sum_{k=5..n} binomial(n-1,k-1) * a(n-k). - Ilya Gutkovskiy, Nov 20 2020
Showing 1-5 of 5 results.