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.

A362247 Expansion of e.g.f. exp(x * exp(x * (exp(x) - 1))).

Original entry on oeis.org

1, 1, 1, 7, 37, 201, 1531, 12433, 112729, 1158769, 12920311, 157007841, 2063354437, 29052921769, 436908104179, 6981843029281, 118083965782321, 2106973566128865, 39538081855597807, 778216030845226561, 16027517577057849181, 344635879922587951321
Offset: 0

Views

Author

Seiichi Manyama, Apr 12 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x*exp(x*(exp(x)-1)))))

Formula

a(n) = n! * Sum_{i=0..n} ( Sum_{j=0..n-i} i^j * Stirling2(n-i-j,j)/(n-i-j)! )/i!.

A347726 Expansion of e.g.f.: exp(x / (1-x)^x).

Original entry on oeis.org

1, 1, 1, 7, 37, 221, 1801, 15709, 157641, 1775521, 21898801, 296379931, 4346295757, 68682481141, 1163591541113, 21024039322441, 403559222086801, 8199021870113985, 175746277620520417, 3963144157484213359, 93778090395227788021, 2323080237693908254381
Offset: 0

Views

Author

Seiichi Manyama, Sep 11 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[0] = 1; a[n_] := n! * Sum[(-1)^(n - i) * Sum[i^j * StirlingS1[n - i - j, j]/(n - i - j)!, {j, 0, n - i}]/i!, {i, 1, n}]; Array[a, 20, 0] (* Amiram Eldar, Sep 11 2021 *)
  • PARI
    a(n) = n!*sum(i=0, n, (-1)^(n-i)*sum(j=0, n-i, i^j*stirling(n-i-j, j, 1)/(n-i-j)!)/i!);
    
  • PARI
    my(N=40, x='x+O('x^N)); Vec(serlaplace(exp(x/(1-x)^x)))

Formula

a(n) = n! * Sum_{i=0..n} (-1)^(n-i) * ( Sum_{j=0..n-i} i^j * Stirling1(n-i-j,j)/(n-i-j)! )/i!.

A362238 Expansion of e.g.f.: 1/(1 - x*(1+x)^x).

Original entry on oeis.org

1, 1, 2, 12, 60, 460, 3900, 39438, 456288, 5896224, 85230000, 1349017560, 23353941600, 437432418696, 8828284404576, 190867622500800, 4401749312069760, 107859517575659520, 2798352667710645120, 76636669899079699776, 2209235394261812751360
Offset: 0

Views

Author

Seiichi Manyama, Apr 12 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x*(1+x)^x)))

Formula

a(n) = n! * Sum_{i=0..n} Sum_{j=0..n-i} i^j * Stirling1(n-i-j,j)/(n-i-j)!.

A354612 Expansion of e.g.f. exp(f(x) - 1) where f(x) = (1 + x)^x = e.g.f. for A007113.

Original entry on oeis.org

1, 0, 2, -3, 32, -150, 1404, -11340, 120448, -1319976, 16600320, -223664760, 3300331704, -52223268240, 887583503520, -16071609481200, 309263446333440, -6296705309543040, 135262191966465600, -3056359409652695040, 72462969268541596800
Offset: 0

Views

Author

Seiichi Manyama, Jul 08 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp((1+x)^x-1)))
    
  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, j!*sum(k=0, j\2, stirling(j-k, k, 1)/(j-k)!)*binomial(i-1, j-1)*v[i-j+1])); v;

Formula

a(0) = 1; a(n) = Sum_{k=1..n} A007113(k) * binomial(n-1,k-1) * a(n-k).
Showing 1-4 of 4 results.