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 1-6 of 6 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

A335975 Square array T(n,k), n>=0, k>=0, read by antidiagonals downwards, where column k is the expansion of e.g.f. exp(k*(exp(x) - 1) + x).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 5, 1, 1, 4, 11, 15, 1, 1, 5, 19, 47, 52, 1, 1, 6, 29, 103, 227, 203, 1, 1, 7, 41, 189, 622, 1215, 877, 1, 1, 8, 55, 311, 1357, 4117, 7107, 4140, 1, 1, 9, 71, 475, 2576, 10589, 29521, 44959, 21147, 1, 1, 10, 89, 687, 4447, 23031, 88909, 227290, 305091, 115975, 1
Offset: 0

Views

Author

Seiichi Manyama, Jul 03 2020

Keywords

Examples

			Square array begins:
  1,   1,    1,     1,     1,      1,      1, ...
  1,   2,    3,     4,     5,      6,      7, ...
  1,   5,   11,    19,    29,     41,     55, ...
  1,  15,   47,   103,   189,    311,    475, ...
  1,  52,  227,   622,  1357,   2576,   4447, ...
  1, 203, 1215,  4117, 10589,  23031,  44683, ...
  1, 877, 7107, 29521, 88909, 220341, 478207, ...
		

Crossrefs

Columns k=0-4 give: A000012, A000110(n+1), A035009(n+1), A078940, A078945.
Main diagonal gives A334240.

Programs

  • Mathematica
    T[0, k_] := 1; T[n_, k_] := T[n - 1, k] + k * Sum[T[j, k] * Binomial[n - 1, j], {j, 0, n - 1}]; Table[T[n - k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Amiram Eldar, Jul 03 2020 *)

Formula

T(0,k) = 1 and T(n,k) = T(n-1,k) + k * Sum_{j=0..n-1} binomial(n-1,j) * T(j,k) for n > 0.
T(n,k) = exp(-k) * Sum_{j>=0} (j + 1)^n * k^j / j!.

A309775 Expansion of e.g.f. exp(2 * (1 - exp(x)) + x).

Original entry on oeis.org

1, -1, -1, 3, 7, -13, -89, -45, 1191, 4723, -6873, -143597, -499289, 1843891, 28132391, 104223059, -508838745, -8597456141, -39770287321, 158845792147, 3788893515687, 23979078221619, -38626203043289, -2200108609291821, -19878849864738137, -27269435066568845
Offset: 0

Views

Author

Seiichi Manyama, Jul 06 2020

Keywords

Crossrefs

Column k=2 of A335977.
Cf. A335980.

Programs

  • Mathematica
    m = 25; Range[0, m]! * CoefficientList[Series[Exp[2 * (1 - Exp[x]) + x], {x, 0, m}], x] (* Amiram Eldar, Jul 06 2020 *)
    Table[Sum[Binomial[n, k] * BellB[k, -2], {k, 0, n}], {n, 0, 30}] (* Vaclav Kotesovec, Jul 06 2020 *)
  • PARI
    N=40; x='x+O('x^N); Vec(serlaplace(exp(2*(1-exp(x))+x)))

Formula

a(0) = 1 and a(n) = a(n-1) - 2 * Sum_{k=0..n-1} binomial(n-1,k) * a(k) for n > 0.
a(n) = exp(2) * Sum_{k>=0} (k + 1)^n * (-2)^k / k!.
a(n) = Sum_{k=0..n} binomial(n,k) * Bell(k, -2). - Vaclav Kotesovec, Jul 06 2020

A341287 Triangle read by rows: T(n,k) = Sum_{i=0..n-1} binomial(n-1, i)*T(n-1-i,k-1) - Sum_{i=1..n-1} binomial(n-1,i)*T(n-1-i,k) for 1 <= k <= n+1 with T(0,1) = 1 (and T(n,k) = 0 otherwise).

Original entry on oeis.org

1, 0, 1, -1, 1, 1, -1, -2, 3, 1, 2, -9, 1, 6, 1, 9, -9, -25, 15, 10, 1, 9, 50, -104, -20, 50, 15, 1, -50, 267, -98, -364, 105, 119, 21, 1, -267, 413, 1163, -1610, -539, 574, 238, 28, 1, -413, -2180, 7569, -1511, -6636, 903, 1806, 426, 36, 1, 2180, -17731, 17491, 29580, -32570, -12957, 8757, 4500, 705, 45, 1
Offset: 0

Views

Author

Petros Hadjicostas, Feb 08 2021

Keywords

Comments

To agree with Knopfmacher and Mays (2001), the rows start at n = 0 while the columns start at k = 1.
The row sums equal 1.
"Let G be a labeled graph, with edge set E(G) and vertex set V(G). A composition of G is a partition of V(G) into vertex sets of connected induced subgraphs of G." "We will denote by C(G) the number of distinct compositions that exist for a given graph G." By Theorem 10 in Knofmacher and Mays (2001), C(K_{n,k}) = Sum_{i=1..n+1} T(n,i)*i^k, where K_{n,k} is the bipartite graph with n+k vertices and n*k edges. For values of C(K_{n,k}), see the table on p. 10 of the paper.
We have C(K_{n,k}) = A265417(n,k).
By symmetry, Sum_{i=1..n+1} T(n,i)*i^k = C(K_{n,k}) = C(K_{k,n}) = Sum_{i=1..k+1} T(k,i)*i^n for n, k >= 1.
Denote the bivariate e.g.f.-o.g.f by A(x,y) = Sum_{n>=0,k>=1} T(n,k)*(x^n/n!)*y^k. Using the definition of T(n,k) and standard manipulations of generating functions, one can prove that A(x,y) = y + int_{w=0..x} A(w,y)*((y-1)*exp(w) + 1) dw. This leads to the initial condition A(0,y) = y and the differential equation dA(x,y)/dx = A(x,y)*((y-1)*exp(x) + 1). Solving this differential equation (for a fixed y), we get A(x,y) = y*exp((1 - y)*(1 - exp(x)) + x). (The bivariate e.g.f.-o.g.f was originally guessed due to the contributions of Seiichi Manyama in A335977.)

Examples

			Triangle T(n,k) with rows n >= 0 and columns 1 <= k <= n+1 begins:
      1,
      0,     1,
     -1,     1,    1,
     -1,    -2,    3,     1,
      2,    -9,    1,     6,     1,
      9,    -9,  -25,    15,    10,   1,
      9,    50, -104,   -20,    50,  15,    1,
    -50,   267,  -98,  -364,   105, 119,   21,   1,
   -267,   413, 1163, -1610,  -539, 574,  238,  28,  1,
   -413, -2180, 7569, -1511, -6636, 903, 1806, 426, 36, 1,
   ...
		

Crossrefs

Programs

  • Maple
    egf := k-> (exp(x)-1)^(k-1)/(k-1)!*exp(x-(exp(x)-1)):
    A341287 := (n, k)-> n! * coeff(series(egf(k), x, n+1), x, n):
    seq(print(seq(A341287(n, k), k=1..n+1)), n=0..9); # Mélika Tebni, Apr 20 2022

Formula

Sum_{k=1..n+1} (-1)^(k-1)*T(n,k) = A309775(n) for n >= 0.
Sum_{k=1..n+1} (-m)^(k-1)*T(n,k) = A335977(n,m+1) for m >= 1 and n >= 0.
T(n,n+1) = 1 and T(n,n) = A000217(n-1) = n*(n-1)/2 for n >= 1.
T(n,1) = -A000587(n+1) for n >= 0 (complementary Bell numbers).
T(n,2) = -T(n+1,1) for n >= 1.
Bivariate e.g.f.-o.g.f: Sum_{n>=0,k>=1} T(n,k)*(x^n/n!)*y^k = y*exp((1 - y)*(1 -exp(x)) + x).
T(n,k) = Sum_{j=1..n+1} binomial(j - 1, k - 1)*(-1)^(j - k)*Stirling2(n + 1, j) for n >= 0 and 1 <= k <= n+1, where Stirling2(n,k) = A048993(n,k). (This is a modification of a formula in Section 4 of Huq (2007).)
From Mélika Tebni, Apr 20 2022: (Start)
T(n, k) = Sum_{j=0..n} A129334(n, j)*Stirling2(j+1, k) for n >= 0 and 1 <= k <= n+1.
E.g.f. column k: (exp(x) - 1)^(k-1) / (k-1)!*exp(x - (exp(x) - 1)), k >= 1. (End)

A320432 Expansion of e.g.f. exp(3 * (1 - exp(x)) + x).

Original entry on oeis.org

1, -2, 1, 7, -8, -65, 37, 1024, 1351, -19001, -92618, 232513, 4087189, 9953926, -123909155, -1170342533, -676144160, 62840385619, 490129709977, -551829062288, -40624407525941, -305175084654341, 698633855671510, 34571970743398621, 278738497423756153, -663168571756087538
Offset: 0

Views

Author

Seiichi Manyama, Jul 06 2020

Keywords

Crossrefs

Column k=3 of A335977.

Programs

  • Mathematica
    m = 25; Range[0, m]! * CoefficientList[Series[Exp[3 * (1 - Exp[x]) + x], {x, 0, m}], x] (* Amiram Eldar, Jul 06 2020 *)
    Table[Sum[Binomial[n, k] * BellB[k, -3], {k, 0, n}], {n, 0, 30}] (* Vaclav Kotesovec, Jul 06 2020 *)
  • PARI
    N=40; x='x+O('x^N); Vec(serlaplace(exp(3*(1-exp(x))+x)))

Formula

a(0) = 1 and a(n) = a(n-1) - 3 * Sum_{k=0..n-1} binomial(n-1,k) * a(k) for n > 0.
a(n) = exp(3) * Sum_{k>=0} (k + 1)^n * (-3)^k / k!.
a(n) = Sum_{k=0..n} binomial(n,k) * Bell(k, -3). - Vaclav Kotesovec, Jul 06 2020

A320433 Expansion of e.g.f. exp(4 * (1 - exp(x)) + x).

Original entry on oeis.org

1, -3, 5, 5, -43, -27, 597, 805, -11883, -40475, 265685, 2133157, -3405803, -107760283, -301542315, 4458255397, 42421260949, -45046794011, -3365690666283, -19844416105563, 138274174035221, 2917746747446373, 11092963732101461, -207438902364296411, -3205301465165742187
Offset: 0

Views

Author

Seiichi Manyama, Jul 06 2020

Keywords

Crossrefs

Column k=4 of A335977.

Programs

  • Mathematica
    m = 24; Range[0, m]! * CoefficientList[Series[Exp[4 * (1 - Exp[x]) + x], {x, 0, m}], x] (* Amiram Eldar, Jul 06 2020 *)
    Table[Sum[Binomial[n, k] * BellB[k, -4], {k, 0, n}], {n, 0, 30}] (* Vaclav Kotesovec, Jul 06 2020 *)
  • PARI
    N=40; x='x+O('x^N); Vec(serlaplace(exp(4*(1-exp(x))+x)))

Formula

a(0) = 1 and a(n) = a(n-1) - 4 * Sum_{k=0..n-1} binomial(n-1,k) * a(k) for n > 0.
a(n) = exp(4) * Sum_{k>=0} (k + 1)^n * (-4)^k / k!.
a(n) = Sum_{k=0..n} binomial(n,k) * Bell(k, -4). - Vaclav Kotesovec, Jul 06 2020
Showing 1-6 of 6 results.