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.

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A367473 Expansion of e.g.f. 1 / (4 - 3 * exp(x))^3.

Original entry on oeis.org

1, 9, 117, 1953, 39645, 946089, 25926597, 801869553, 27618402285, 1048096422009, 43444114011477, 1952712851250753, 94592798546953725, 4912513525545837129, 272265236648295312357, 16039329591716508497553, 1000809252891040145821965
Offset: 0

Views

Author

Seiichi Manyama, Nov 19 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, 3^k*(k+2)!*stirling(n, k, 2))/2;

Formula

a(n) = (1/2) * Sum_{k=0..n} 3^k * (k+2)! * Stirling2(n,k).
a(0) = 1; a(n) = 3*Sum_{k=1..n} (2*k/n + 1) * binomial(n,k) * a(n-k).
a(0) = 1; a(n) = 9*a(n-1) - 4*Sum_{k=1..n-1} (-1)^k * binomial(n-1,k) * a(n-k).

A375949 Expansion of e.g.f. 1 / (4 - 3 * exp(x))^(4/3).

Original entry on oeis.org

1, 4, 32, 368, 5520, 102064, 2242832, 57095728, 1652211600, 53559908784, 1922581295632, 75700072208688, 3243905700776080, 150289130386531504, 7485459789379535632, 398857142195958963248, 22639650637589839298960, 1363772478150606703714224
Offset: 0

Views

Author

Seiichi Manyama, Sep 03 2024

Keywords

Crossrefs

Programs

  • Mathematica
    nmax=17; CoefficientList[Series[1 / (4 - 3 * Exp[x])^(4/3),{x,0,nmax}],x]*Range[0,nmax]! (* Stefano Spezia, Sep 03 2024 *)
  • PARI
    a007559(n) = prod(k=0, n-1, 3*k+1);
    a(n) = sum(k=0, n, a007559(k+1)*stirling(n, k, 2));

Formula

a(n) = Sum_{k=0..n} A007559(k+1) * Stirling2(n,k).
a(n) ~ 3 * sqrt(Pi) * n^(n + 5/6) / (2^(13/6) * Gamma(1/3) * log(4/3)^(n + 4/3) * exp(n)). - Vaclav Kotesovec, Sep 06 2024

A384325 Expansion of Product_{k>=1} 1/(1 - k*x)^((3/4)^k).

Original entry on oeis.org

1, 12, 114, 1084, 11319, 136920, 1981228, 34705656, 731268315, 18203860748, 524073230394, 17111173850652, 623571696107069, 25046605210733184, 1097919954149781264, 52109508350206511840, 2660615337817983390318, 145353541761618312219336
Offset: 0

Views

Author

Seiichi Manyama, May 26 2025

Keywords

Crossrefs

Programs

  • Mathematica
    terms = 20; A[] = 1; Do[A[x] = -3*A[x] + 4*A[x/(1-x)]^(3/4) / (1-x)^3 + O[x]^j // Normal, {j, 1, terms}]; CoefficientList[A[x], x] (* Vaclav Kotesovec, May 27 2025 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(exp(4*sum(k=1, N, sum(j=0, k, 3^j*j!*stirling(k, j, 2))*x^k/k)))

Formula

G.f. A(x) satisfies A(x) = A(x/(1-x))^(3/4) / (1-x)^3.
G.f.: exp(4 * Sum_{k>=1} A032033(k) * x^k/k).
G.f.: B(x)^12, where B(x) is the g.f. of A090353.
a(n) ~ (n-1)! / log(4/3)^(n+1). - Vaclav Kotesovec, May 27 2025

A375952 Expansion of e.g.f. 1 / (4 - 3 * exp(x))^(5/3).

Original entry on oeis.org

1, 5, 45, 565, 9085, 177925, 4106445, 109105365, 3279219485, 109983317925, 4071784884845, 164919693538165, 7253726995805885, 344284133391481925, 17538600019076063245, 954467594134586386965, 55263075631036363208285, 3391909484128563111709925
Offset: 0

Views

Author

Seiichi Manyama, Sep 03 2024

Keywords

Crossrefs

Programs

  • Mathematica
    nmax=17; CoefficientList[Series[1 / (4 - 3 * Exp[x])^(5/3),{x,0,nmax}],x]*Range[0,nmax]! (* Stefano Spezia, Sep 03 2024 *)
  • PARI
    a008544(n) = prod(k=0, n-1, 3*k+2);
    a(n) = sum(k=0, n, a008544(k+1)*stirling(n, k, 2))/2;

Formula

a(n) = (1/2) * Sum_{k=0..n} A008544(k+1) * Stirling2(n,k).

A384364 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where A(n,k) = Sum_{i=0..k*n} 3^i * Sum_{j=0..i} (-1)^j * binomial(i,j) * binomial(i-j,n)^k.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 21, 9, 1, 1, 219, 657, 27, 1, 1, 3045, 119241, 22869, 81, 1, 1, 52923, 40365873, 80850987, 836001, 243, 1, 1, 1103781, 21955523049, 747786838869, 60579666801, 31436181, 729, 1, 1, 26857659, 17512689629457, 14298291269335467, 16117269494868801, 48066954848379, 1204022961, 2187, 1
Offset: 0

Views

Author

Seiichi Manyama, May 27 2025

Keywords

Examples

			Square array begins:
  1,  1,      1,           1,                 1, ...
  1,  3,     21,         219,              3045, ...
  1,  9,    657,      119241,          40365873, ...
  1, 27,  22869,    80850987,      747786838869, ...
  1, 81, 836001, 60579666801, 16117269494868801, ...
		

Crossrefs

Columns k=0..2 give A000012, A000244, 3^n * A084768(n).
Rows n=0..1 give A000012, A032033.

Programs

  • PARI
    a(n, k) = sum(i=0, k*n, 3^i*sum(j=0, i, (-1)^j*binomial(i, j)*binomial(i-j, n)^k));

Formula

A(n,k) = (1/4) * Sum_{j>=0} (3/4)^j * binomial(j,n)^k.

A238466 Generalized ordered Bell numbers Bo(9,n).

Original entry on oeis.org

1, 9, 171, 4869, 184851, 8772309, 499559571, 33190014069, 2520110222451, 215270320769109, 20431783142389971, 2133148392099721269, 242954208655633344051, 29977118969127060357909, 3983272698956314883956371, 567091857051921058649396469
Offset: 0

Views

Author

Vincenzo Librandi, Mar 18 2014

Keywords

Comments

Row 9 of array A094416, which has more information.

Crossrefs

Programs

  • Magma
    m:=20; R:=LaurentSeriesRing(RationalField(), m); b:=Coefficients(R!(1/(10 - 9*Exp(x)))); [Factorial(n-1)*b[n]: n in [1..m]];
  • Mathematica
    t=30; Range[0, t]! CoefficientList[Series[1/(10 - 9 Exp[x]), {x, 0, t}], x]

Formula

E.g.f.: 1/(10 - 9*exp(x)).
a(n) ~ n! / (10*(log(10/9))^(n+1)). - Vaclav Kotesovec, Mar 20 2014
a(0) = 1; a(n) = 9*a(n-1) - 10*Sum_{k=1..n-1} (-1)^k * binomial(n-1,k) * a(n-k). - Seiichi Manyama, Nov 17 2023

A238467 Generalized ordered Bell numbers Bo(10,n).

Original entry on oeis.org

1, 10, 210, 6610, 277410, 14553010, 916146210, 67285818610, 5647734061410, 533307215001010, 55954905981282210, 6457903731351210610, 813080459351919805410, 110901542660769629769010, 16290196917457939734258210
Offset: 0

Views

Author

Vincenzo Librandi, Mar 18 2014

Keywords

Comments

Row 10 of array A094416, which has more information.

Crossrefs

Programs

  • Magma
    m:=20; R:=LaurentSeriesRing(RationalField(), m); b:=Coefficients(R!(1/(11 - 10*Exp(x)))); [Factorial(n-1)*b[n]: n in [1..m]];
  • Mathematica
    t=30; Range[0, t]! CoefficientList[Series[1/(11 - 10 Exp[x]), {x, 0, t}], x]

Formula

E.g.f.: 1/(11 - 10*exp(x)).
a(n) ~ n! / (11*(log(11/10))^(n+1)). - Vaclav Kotesovec, Mar 20 2014
a(0) = 1; a(n) = 10*a(n-1) - 11*Sum_{k=1..n-1} (-1)^k * binomial(n-1,k) * a(n-k). - Seiichi Manyama, Nov 17 2023

A368322 Expansion of e.g.f. exp(2*x) / (4 - 3*exp(x)).

Original entry on oeis.org

1, 5, 37, 389, 5413, 94085, 1962277, 47746949, 1327769893, 41538664325, 1443908686117, 55210237509509, 2302968844974373, 104068337416767365, 5064468256286449957, 264065894676248072069, 14686540175450593986853, 867871886679723760867205
Offset: 0

Views

Author

Seiichi Manyama, Dec 21 2023

Keywords

Crossrefs

Programs

  • PARI
    b(n, t) = sum(k=0, n, t^k*k!*stirling(n, k, 2));
    a(n, m=2, t=3) = my(u=1+1/t); u^m*b(n, t)-(1/t)*sum(j=0, m-1, u^j*(m-1-j)^n);

Formula

a(n) = 2^n + 3 * Sum_{k=1..n} binomial(n,k) * a(n-k).
a(n) = (16/9)*A032033(n) - (1/3)*(1 + (4/3)*0^n).

A368323 Expansion of e.g.f. exp(3*x) / (4 - 3*exp(x)).

Original entry on oeis.org

1, 6, 48, 516, 7212, 125436, 2616348, 63662556, 1770359772, 55384885596, 1925211581148, 73613650011996, 3070625126631132, 138757783222353756, 6752624341715261148, 352087859568330751836, 19582053567267458627292, 1157162515572965014445916
Offset: 0

Views

Author

Seiichi Manyama, Dec 21 2023

Keywords

Crossrefs

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[Exp[3x]/(4-3Exp[x]),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Aug 18 2025 *)
  • PARI
    b(n, t) = sum(k=0, n, t^k*k!*stirling(n, k, 2));
    a(n, m=3, t=3) = my(u=1+1/t); u^m*b(n, t)-(1/t)*sum(j=0, m-1, u^j*(m-1-j)^n);

Formula

a(n) = 3^n + 3 * Sum_{k=1..n} binomial(n,k) * a(n-k).
a(n) = (64/27)*A032033(n) - (1/3)*(2^n + 4/3 + (16/9)*0^n).

A368324 Expansion of e.g.f. exp(4*x) / (4 - 3*exp(x)).

Original entry on oeis.org

1, 7, 61, 679, 9589, 167167, 3488221, 84882679, 2360477509, 73846507567, 2566948755181, 98151533290279, 4094166835331029, 185010377629273567, 9003499122285420541, 469450479424436219479, 26109404756356597154149, 1542883354097286642881167
Offset: 0

Views

Author

Seiichi Manyama, Dec 21 2023

Keywords

Crossrefs

Programs

  • PARI
    b(n, t) = sum(k=0, n, t^k*k!*stirling(n, k, 2));
    a(n, m=4, t=3) = my(u=1+1/t); u^m*b(n, t)-(1/t)*sum(j=0, m-1, u^j*(m-1-j)^n);

Formula

a(n) = 4^n + 3 * Sum_{k=1..n} binomial(n,k) * a(n-k).
a(n) = (256/81)*A032033(n) - (1/3)*(3^n + (4/3)*2^n + 16/9 + (64/27)*0^n).
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