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 1-9 of 9 results.

A101054 E.g.f.: exp(exp(x)-1)/(1-x)^2.

Original entry on oeis.org

1, 3, 12, 59, 343, 2302, 17537, 149711, 1417444, 14755947, 167664955, 2066153410, 27460121377, 391670868279, 5969233120520, 96827494235555, 1665874346755107, 30302732222472482, 581141491978752769, 11719848107849221435, 247960209086201040552, 5491993051193586857235
Offset: 0

Views

Author

Karol A. Penson, Nov 29 2004

Keywords

Comments

Sequence appears in the problem of normal ordering of functions of boson operators.

Crossrefs

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Exp(Exp(x)-1)/(1-x)^2)); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, May 23 2018
  • Maple
    egf := exp(exp(x)-1)/((1-x)^2);
    seq(n!*coeff(series(egf,x,n+1),x,n),n=0..21); # Peter Luschny, Sep 17 2014
  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[Exp[Exp[x] - 1]/(1 - x)^2, {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, May 23 2018 *)
  • PARI
    x='x+O('x^30); Vec(serlaplace(exp(exp(x)-1)/(1-x)^2 )) \\ G. C. Greubel, May 23 2018
    

Formula

a(n) = ((-1)^n*n!/e)*Sum_{k>=0} L(n,-n-2,k)/k!, where L is a generalized Laguerre polynomial.
a(n) = Sum_{k=0..n} binomial(n,k)*(k + 1)!*Bell(n-k), where Bell() = A000110. - Ilya Gutkovskiy, May 24 2018
a(n) ~ exp(exp(1)-1) * n * n!. - Vaclav Kotesovec, Jun 26 2022

A113059 a(n) = n! * Sum_{k=0..n} A000296(k)/k!.

Original entry on oeis.org

1, 1, 3, 10, 44, 231, 1427, 10151, 81923, 740732, 7425042, 81773715, 981864897, 12767876941, 178774288331, 2681781213130, 42909715480460, 729474427239587, 13130613291110603, 249482261007109579, 4989650444408388515, 104782705832468197252, 2305219956684224457858
Offset: 0

Views

Author

Karol A. Penson, Oct 12 2005

Keywords

Comments

Number of set partitions of [n] where the k-th singletons are k-colored and all other blocks are unicolored. - Alois P. Heinz, Apr 29 2025

Crossrefs

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(Exp(Exp(x)-1-x)/(1-x))); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, May 23 2018
  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, k*b(n-1, k+1)+
          add(b(n-j, k)*binomial(n-1, j-1), j=2..n))
        end:
    a:= n-> b(n, 1):
    seq(a(n), n=0..22);  # Alois P. Heinz, Apr 29 2025
    # second Maple program:
    b:= proc(n, k, m) option remember; `if`(n=0, k!, `if`(k>0,
          b(n-1, k-1, m+1)*k, 0)+m*b(n-1, k, m)+b(n-1, k+1, m))
        end:
    a:= n-> b(n, 0$2):
    seq(a(n), n=0..22);  # Alois P. Heinz, Apr 29 2025
  • Mathematica
    With[{nmax = 50}, CoefficientList[Series[Exp[Exp[x] - 1 - x]/(1 - x), {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, May 23 2018 *)
  • PARI
    x='x+O('x^30); Vec(serlaplace( exp(exp(x)-1-x)/(1-x))) \\ G. C. Greubel, May 23 2018
    

Formula

a(n) = (-1)^n*n!*Sum_{k >=0} LaguerreL(n, -n-1, k-1)/k!/exp(1), n>=0.
E.g.f.: exp(exp(x)-1-x)/(1-x).
a(n) ~ exp(exp(1)-2) * n!. - Vaclav Kotesovec, Jun 26 2022

A101055 E.g.f.: exp(exp(x)-1)/(1-x)^3.

Original entry on oeis.org

1, 4, 20, 119, 819, 6397, 55919, 541144, 5746596, 66475311, 832418065, 11222752125, 162133146877, 2499401777680, 40960858008040, 711240364356155, 13045720176453587, 252079975222183461, 5118581045978055067, 108972887981432267708, 2427417968714846394712, 56467770394205361146187
Offset: 0

Views

Author

Karol A. Penson, Nov 29 2004

Keywords

Comments

Sequence appears in the problem of normal ordering of functions of boson operators.

Crossrefs

Programs

  • Mathematica
    With[{nn=30},CoefficientList[Series[Exp[Exp[x]-1]/(1-x)^3,{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Aug 11 2021 *)

Formula

a(n) = ((-1)^n*n!/e)*Sum_{k>=0} L(n,-n-3,k)/k!, where L is a generalized Laguerre polynomial.
a(n) = (1/2)*Sum_{k=0..n} binomial(n,k)*(k + 2)!*Bell(n-k), where Bell() = A000110. - Ilya Gutkovskiy, May 24 2018
a(n) ~ exp(exp(1)-1) * n^2 * n! / 2. - Vaclav Kotesovec, Jun 26 2022

Extensions

Terms after a(15) from Ilya Gutkovskiy, May 24 2018

A367972 Expansion of e.g.f. exp(exp(2*x) - 1)/(1 - x).

Original entry on oeis.org

1, 3, 14, 82, 568, 4504, 40016, 392368, 4198784, 48616320, 604921600, 8043848960, 113785080832, 1705669278720, 27007064393728, 450422751508480, 7893590619881472, 145052304752934912, 2789743827826573312, 56063169473909817344
Offset: 0

Views

Author

Seiichi Manyama, Dec 06 2023

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, ((j-1)!+2^j)*binomial(i-1, j-1)*v[i-j+1])); v;

Formula

a(0) = 1; a(n) = Sum_{k=1..n} ((k-1)! + 2^k) * binomial(n-1,k-1) * a(n-k).
a(n) = n! * Sum_{k=0..n} 2^k * Bell(k)/k!, where Bell() is A000110.

A305051 a(n) = n! * [x^n] exp(exp(x) - 1)/(1 - x)^n.

Original entry on oeis.org

1, 2, 12, 119, 1655, 29647, 649925, 16852656, 504519916, 17124927207, 649856846635, 27262957861405, 1252893494644357, 62593349657218070, 3377648236341185084, 195782612085816693995, 12131925601060324633027, 800321307922970722566527, 55998398887720317868148977
Offset: 0

Views

Author

Ilya Gutkovskiy, May 24 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Exp[Exp[x] - 1]/(1 - x)^n, {x, 0, n}], {n, 0, 18}]
    Table[(-1)^n n!/Exp[1] Sum[LaguerreL[n,-2 n, k]/k!, {k, 0, Infinity}], {n, 0, 18}]
    Join[{1}, Table[1/(n - 1)! Sum[Binomial[n, k] (n + k - 1)! BellB[n - k], {k, 0, n}], {n, 18}]]

Formula

a(n) = ((-1)^n*n!/exp(1))*Sum_{k>=0} Laguerre(n,-2*n,k)/k!.
a(0) = 1; a(n) = (1/(n - 1)!)*Sum_{k=0..n} binomial(n,k)*(n + k - 1)!*Bell(n-k), where Bell() = A000110.
a(n) ~ c * n^n * 4^n / exp(n), where c = exp(exp(1/2) - 1)/sqrt(2) = 1.3527609882698012767793757868699146219161180684881726130481416807461987206887... - Vaclav Kotesovec, May 11 2021, updated Mar 18 2024

A317366 Expansion of e.g.f. exp(exp(x/(1 - x)) - 1)/(1 - x).

Original entry on oeis.org

1, 2, 8, 47, 359, 3347, 36665, 460098, 6494444, 101708007, 1748263435, 32697711895, 660642793717, 14332871438810, 332186039584768, 8188070581358795, 213821204277955267, 5895325327054011087, 171095582314380667621, 5212792218964517899506, 166321395872186089502972, 5545223090189205308551443
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 26 2018

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; add(binomial(n, k)^2
          *k!*combinat[bell](n-k), k=0..n)
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Jul 26 2018
  • Mathematica
    nmax = 21; CoefficientList[Series[Exp[Exp[x/(1 - x)] - 1]/(1 - x) , {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[Binomial[n, k]^2 k! BellB[n - k], {k, 0, n}], {n, 0, 21}]

Formula

a(n) = Sum_{k=0..n} binomial(n,k)^2*k!*Bell(n-k), where Bell() = A000110.

A367971 Expansion of e.g.f. exp(exp(-x) - 1)/(1 - x).

Original entry on oeis.org

1, 0, 2, 1, 19, 43, 461, 2350, 22940, 185313, 1969105, 20981585, 255992617, 3300259584, 46394533498, 694535043925, 11123040844947, 189008829494295, 3402841007703469, 64648146404160854, 1293014652241452452, 27152832827254344741, 597366828915334031625
Offset: 0

Views

Author

Seiichi Manyama, Dec 06 2023

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, ((j-1)!+(-1)^j)*binomial(i-1, j-1)*v[i-j+1])); v;

Formula

a(0) = 1; a(n) = Sum_{k=1..n} ((k-1)! + (-1)^k) * binomial(n-1,k-1) * a(n-k).
a(n) = n! * Sum_{k=0..n} (-1)^k * Bell(k)/k!, where Bell() is A000110.

A337000 E.g.f.: 1 / ((1 - x)*(2 - exp(x))).

Original entry on oeis.org

1, 2, 7, 34, 211, 1596, 14259, 147106, 1722683, 22591408, 328161643, 5232410646, 90880495347, 1708304787892, 34557610000931, 748647340991818, 17294012137850443, 424368973372593432, 11024176183963527099, 302260934814635426014, 8722906492537092723395
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 10 2020

Keywords

Comments

Exponential convolution of Fubini numbers (A000670) and factorial numbers (A000142).

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[1/((1 - x) (2 - Exp[x])), {x, 0, nmax}], x] Range[0, nmax]!
    Table[n! Sum[HurwitzLerchPhi[1/2, -k, 0]/(2 k!), {k, 0, n}], {n, 0, 20}]
    a[0] = 1; a[n_] := a[n] = 2 n a[n - 1] - Sum[Binomial[n, k]  (k - 1) a[n - k], {k, 2, n}]; Table[a[n], {n, 0, 20}]

Formula

a(n) = n! * Sum_{k=0..n} A000670(k) / k!.
a(0) = 1; a(n) = 2 * n * a(n-1) - Sum_{k=2..n} binomial(n,k) * (k-1) * a(n-k).
a(n) ~ n! / (2 * (1 - log(2)) * log(2)^(n+1)). - Vaclav Kotesovec, Aug 09 2021

A356559 a(n) = exp(-1) * n! * Sum_{k>=0} Laguerre(n,k) / k!.

Original entry on oeis.org

1, 0, 0, 1, 7, 43, 281, 2056, 17004, 157809, 1622515, 18245335, 222004597, 2898508416, 40343356184, 595578837205, 9287308741827, 152459628788599, 2627373030049669, 47425289731038656, 895098852673047772, 17644305594671247141, 363065584549610882703, 7799894520723959486795
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 12 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Exp[-1] n! Sum[LaguerreL[n, k]/k!, {k, 0, Infinity}], {n, 0, 23}]
    nmax = 23; CoefficientList[Series[Exp[Exp[-x/(1 - x)] - 1]/(1 - x), {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[(-1)^(n - k) Binomial[n, k]^2 k! BellB[n - k], {k, 0, n}], {n, 0, 23}]
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace(exp(exp(-x/(1 - x)) - 1) / (1 - x))) \\ Michel Marcus, Aug 12 2022

Formula

E.g.f.: exp(exp(-x/(1 - x)) - 1) / (1 - x).
a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n,k)^2 * k! * Bell(n-k).
Showing 1-9 of 9 results.