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.

A294042 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f.: exp((1+x)^k - 1).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 6, 1, 0, 1, 4, 15, 20, 1, 0, 1, 5, 28, 87, 76, 1, 0, 1, 6, 45, 232, 585, 312, 1, 0, 1, 7, 66, 485, 2248, 4383, 1384, 1, 0, 1, 8, 91, 876, 6145, 24544, 35919, 6512, 1, 0, 1, 9, 120, 1435, 13716, 88245, 295456, 318195, 32400, 1, 0
Offset: 0

Views

Author

Seiichi Manyama, Oct 22 2017

Keywords

Examples

			Square array A(n,k) begins:
   1, 1,   1,    1,     1,     1, ...
   0, 1,   2,    3,     4,     5, ...
   0, 1,   6,   15,    28,    45, ...
   0, 1,  20,   87,   232,   485, ...
   0, 1,  76,  585,  2248,  6145, ...
   0, 1, 312, 4383, 24544, 88245, ...
		

Crossrefs

Columns k=0..5 give A000007, A000012, A000898, A192989, A202824, A202825.
Rows n=0..2 give A000012, A001477, A000384.
Main diagonal gives A294045.

Formula

A(0,k) = 1 and A(n,k) = k * (n-1)! * Sum_{j=1..min(k,n)} binomial(k-1,j-1) * A(n-j,k)/(n-j)! for n > 0.
A(n,k) = Sum_{j=0..n} k^j * Stirling1(n,j) * Bell(j). - Seiichi Manyama, Jan 31 2024

A202825 Expansion of e.g.f.: exp( (1+x)^5 - 1 ).

Original entry on oeis.org

1, 5, 45, 485, 6145, 88245, 1403725, 24383525, 457473825, 9191615525, 196455592525, 4442277025125, 105787516038625, 2642880807687125, 69040011233566125, 1880443426122681125, 53268012941536530625, 1565875625728027213125, 47673392561258073158125
Offset: 0

Views

Author

Paul D. Hanna, Dec 25 2011

Keywords

Examples

			E.g.f.: A(x) = 1 + 5*x + 45*x^2/2! + 485*x^3/3! + 6145*x^4/4! +...
where A(x) = exp(5*x + 10*x^2 + 10*x^3 + 5*x^4 + x^5).
		

Crossrefs

Programs

  • GAP
    List([0..20], n-> Sum([0..n], k-> (-1)^(n-k)*5^k*Bell(k)* Stirling1(n,k) )); # G. C. Greubel, Jul 25 2019
  • Magma
    [(&+[5^k*Bell(k)*StirlingFirst(n,k): k in [0..n]]): n in [0..20]]; // G. C. Greubel, Jul 25 2019
    
  • Mathematica
    Table[Sum[StirlingS1[n, k] 5^k BellB[k], {k, 0, n}], {n, 0, 20}] (* Emanuele Munarini, Sep 06 2017 *)
  • Maxima
    makelist(sum(stirling1(n,k)*5^k*belln(k),k,0,n),n,0,12); /* Emanuele Munarini, Sep 06 2017 */
    
  • PARI
    {a(n)=n!*polcoeff(exp((1+x +x*O(x^n))^5-1),n)}
    
  • PARI
    {Stirling1(n, k)=n!*polcoeff(binomial(x, n), k)}
    {Bell(n)=n!*polcoeff(exp(exp(x+x*O(x^n))-1), n)}
    {a(n)=sum(k=0, n, Stirling1(n, k)*Bell(k) * 5^k)}
    
  • Sage
    [sum((-1)^(n-k)*5^k*bell_number(k)*stirling_number1(n,k) for k in (0..n)) for n in (0..20)] # G. C. Greubel, Jul 25 2019
    

Formula

a(n) = Sum_{k=0..n} Stirling1(n, k)*Bell(k) * 5^k.
a(n+5) - 5*a(n+4) - 20*(n+4)*a(n+3) - 30*(n+3)*(n+4)*a(n+2) - 20*(n+2)*(n+3)*(n+4)* a(n+1) - 5*(n+1)*(n+2)*(n+3)*(n+4)*a(n) = 0. - Emanuele Munarini, Sep 06 2017

A202826 E.g.f.: exp( 1/(1-x)^3 - 1 ).

Original entry on oeis.org

1, 3, 21, 195, 2241, 30483, 476469, 8383203, 163532385, 3496040163, 81159271029, 2030708891907, 54427341596769, 1554460972941555, 47097454520401749, 1507969940021725347, 50850987639474121281, 1800630391669594010307, 66775808799868618561365
Offset: 0

Views

Author

Paul D. Hanna, Dec 25 2011

Keywords

Examples

			E.g.f.: A(x) = 1 + 3*x + 21*x^2/2! + 195*x^3/3! + 2241*x^4/4! +...
where
log(A(x)) = 3*x + 6*x^2 + 10*x^3 + 15*x^4 + 21*x^5 + 28*x^6 +...
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[E^(1/(1-x)^3-1), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Feb 12 2013 *)
    Table[Sum[Abs[StirlingS1[n, k]] 3^k BellB[k], {k, 0, n}], {n, 0, 100}] (* Emanuele Munarini, Sep 01 2017 *)
  • Maxima
    makelist(sum(abs(stirling1(n,k))*3^k*belln(k),k,0,n),n,0,12); /* Emanuele Munarini, Sep 01 2017 */
  • PARI
    {a(n)=n!*polcoeff(exp(1/(1-x +x*O(x^n))^3-1),n)}
    
  • PARI
    {Stirling1(n, k)=n!*polcoeff(binomial(x, n), k)}
    {Bell(n)=n!*polcoeff(exp(exp(x+x*O(x^n))-1), n)}
    {a(n)=sum(k=0, n, Stirling1(n, k)*Bell(k) *(-1)^(n-k)*3^k)}
    

Formula

a(n) = Sum_{k=0..n} Stirling1(n, k) * Bell(k) * (-1)^(n-k) * 3^k.
a(n) ~ n! * 1/2*3^(1/8)*exp(sqrt(3*n)/2 -3/4 + (3*n)^(1/4)*(4/3*sqrt(n) + 5/24*sqrt(3)) )/(sqrt(2*Pi)*n^(5/8)) * (1 + 871/2560*(3/n)^(1/4)). - Vaclav Kotesovec, Feb 12 2013
a(n+4) - (4*n+15)*a(n+3) + 6*(n+2)*(n+3)*a(n+2) - 4*(n+1)*(n+2)+(n+3)*a(n+1) + n*(n+1)*(n+2)*(n+3)*a(n) = 0. - Emanuele Munarini, Sep 01 2017

Extensions

Example corrected by Vaclav Kotesovec, Feb 12 2013

A369752 Expansion of e.g.f. exp(1 - (1+x)^4).

Original entry on oeis.org

1, -4, 4, 56, -104, -2464, 1696, 181184, 462016, -17069824, -141580544, 1593913856, 33015560704, -47193585664, -6973651011584, -50207289585664, 1214484253413376, 25500259291480064, -72069247145590784, -8696105637665603584, -81680899029758541824
Offset: 0

Views

Author

Seiichi Manyama, Jan 30 2024

Keywords

Crossrefs

Column k=4 of A369738.

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[Exp[1-(1+x)^4],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Mar 29 2024 *)
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(1-(1+x)^4)))

Formula

a(0) = 1; a(n) = -4 * (n-1)! * Sum_{k=1..min(4,n)} binomial(3,k-1) * a(n-k)/(n-k)!.
a(n) = Sum_{k=0..n} 4^k * Stirling1(n,k) * A000587(k).
D-finite with recurrence a(n) +4*a(n-1) +12*(n-1)*a(n-2) +12*(n-1)*(n-2)*a(n-3) +4*(n-1)*(n-2)*(n-3)*a(n-4)=0. - R. J. Mathar, Feb 02 2024
Showing 1-4 of 4 results.