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.

A138734 a(n) = n-th term of the (n+1)-th inverse binomial transform of A138737 for n>=0.

Original entry on oeis.org

1, 0, 4, 0, 176, 0, 24192, 0, 6966528, 0, 3459768320, 0, 2642804895744, 0, 2880385956446208, 0, 4248075487709560832, 0, 8150896954121845211136, 0, 19738484719911211593891840, 0, 58891248341123034677673721856, 0
Offset: 0

Views

Author

Paul D. Hanna, Apr 05 2008

Keywords

Comments

The n-th term of the n-th inverse binomial transform of A138737 = (n+1)^(n-1) for n>=0.

Examples

			E.g.f.: A(x) = 1 + 4*x^2/2! + 176*x^4/4! + 24192*x^6/6! + 6966528*x^8/8! +...
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[-LambertW[x]*LambertW[-x]/x^2, {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Oct 08 2013 *)
  • PARI
    {a(n)=local(A=[1]);for(k=1,n,A=concat(A,0); A[k+1]=(k+1)^(k-1)-polcoeff(subst(Ser(A),x,x/(1+k*x+x*O(x^k)))/(1+k*x),k)); polcoeff(subst(Ser(A),x,x/(1+(n+1)*x+x*O(x^n)))/(1+(n+1)*x),n)}
    
  • PARI
    {a(n)=sum(k=0, n, (-1)^k*binomial(n,k)*(k+1)^(k-1)*(n-k+1)^(n-k-1))}
    
  • PARI
    {a(n)=local(LW=sum(m=1,n+1,m^(m-1)*x^m/m!)+x^2*O(x^n));n!*polcoeff(-LW*subst(LW,x,-x)/x^2,n)}
    
  • PARI
    {a(n)=n!*polcoeff(exp(sum(m=1,n,2*(2*m)^(2*m-1)*x^(2*m)/(2*m)!)+x*O(x^n)),n)}
    
  • PARI
    x='x+O('x^50); Vec(serlaplace(-lambertw(x)*lambertw(-x)/x^2)) \\ G. C. Greubel, Nov 15 2017

Formula

From Paul D. Hanna, Apr 20 2011: (Start)
a(n) = Sum_{k=0..n} (-1)^k*C(n,k) * (k+1)^(k-1) * (n-k+1)^(n-k-1).
E.g.f.: -LambertW(x)*LambertW(-x)/x^2.
E.g.f.: exp( Sum_{n>=1} 2*(2n)^(2n-1) * x^(2n)/(2n)! ). (End)
Let Chw(x) = Sum_{n>=0} (2*n+1)^(2*n-1) * x^(2*n)/(2*n)!
and Shw(x) = Sum_{n>=0} (2*n+2)^(2*n) * x^(2*n+1)/(2*n+1)!
then e.g.f. A(x) = Chw(x)^2 - Shw(x)^2. - Paul D. Hanna, Aug 22 2012
If n is even, a(n) ~ 2*exp(2) * LambertW(exp(-1)) * n^(n-1). - Vaclav Kotesovec, Oct 08 2013

A138736 Inverse binomial transform of A138737.

Original entry on oeis.org

1, 1, 4, 36, 368, 5200, 90432, 1884736, 45817088, 1273874688, 39891461120, 1389816423424, 53334303584256, 2235679577657344, 101651458028158976, 4983219643056537600, 262026143585449607168, 14711289584591513387008
Offset: 0

Views

Author

Paul D. Hanna, Apr 05 2008

Keywords

Comments

The n-th term of the n-th inverse binomial transform of A138737 equals (n+1)^(n-1) for n>=0.
Related to LambertW(-x)/(-x) = Sum_{n>=0} (n+1)^(n-1)*x^n/n!.

Crossrefs

Cf. A138737.

Programs

  • PARI
    {a(n)=local(A=[1]);for(k=1,n,A=concat(A,0); A[k+1]=(k+1)^(k-1)-Vec(subst(Ser(A),x,x/(1+(k-1)*x+x*O(x^k)))/(1+(k-1)*x))[k+1]);A[n+1]}

Formula

O.g.f. satisfies: [x^n] A( x/(1+(n-1)*x) )/(1+(n-1)*x) = (n+1)^(n-1) for n>=0.
E.g.f. satisfies: [x^n] A(x)*exp(-(n-1)*x) = (n+1)^(n-1)/n! for n>=0.
a(n) ~ (1 + LambertW(exp(-1)))^(3/2)*n^(n-1) / (exp(n-2)*LambertW(exp(-1))^(n-1)). - Vaclav Kotesovec, Oct 30 2017

A215882 Expansion of e.g.f.: -LambertW(-x) / LambertW(x).

Original entry on oeis.org

1, 2, 4, 26, 160, 2002, 21184, 395866, 5980160, 149083874, 2933576704, 91549564570, 2222207205376, 83345185392562, 2407376957456384, 105482963294851418, 3534260251308064768, 177194291803516980418, 6757029862401745616896, 381514700506253250858778
Offset: 0

Views

Author

Paul D. Hanna, Aug 25 2012

Keywords

Examples

			E.g.f.: A(x) = 1 + 2*x + 4*x^2/2! + 26*x^3/3! + 160*x^4/4! + 2002*x^5/5! +... such that A(x) = -LambertW(-x)/LambertW(x) where LambertW(x) = x - 2*x^2/2! + 9*x^3/3! - 64*x^4/4! + 625*x^5/5! - 7776*x^6/6! + 117649*x^7/7! - 2097152*x^8/8! +...+ (-n)^(n-1)*x^n/n! +... .
Related expansions: log(A(x)) = 2*x + 18*x^3/3! + 1250*x^5/5! + 235298*x^7/7! + 86093442*x^9/9! +...+ 2*(2*n+1)^(2*n)*x^(2*n+1)/(2*n+1)! +...
		

Crossrefs

Programs

  • GAP
    List([0..20],n->Sum([0..n],k->-(-1)^k*Binomial(n,k)*(k-1)^(k-1)*(n-k+1)^(n-k-1))); # Muniru A Asiru, Feb 20 2018
  • Mathematica
    CoefficientList[Series[-LambertW[-x]/LambertW[x], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Nov 27 2012 *)
  • PARI
    {a(n)=local(LW=sum(m=1, n+1,-(-1)^m*m^(m-1)*x^m/m!)+x^2*O(x^n)); n!*polcoeff(sqrt(-subst(LW, x, -x)/LW), n)}
    
  • PARI
    {a(n)=n!*polcoeff(exp(sum(m=0, n, 2*(2*m+1)^(2*m)*x^(2*m+1)/ (2*m+1)!)+x*O(x^n)), n)}
    
  • PARI
    {a(n)=sum(k=0, n, -(-1)^k*binomial(n, k)*(k-1)^(k-1)*(n-k+1)^(n-k-1))}
    for(n=0,21,print1(a(n),", "))
    
  • PARI
    x='x+O('x^30); Vec(serlaplace(-lambertw(-x)/lambertw(x))) \\ G. C. Greubel, Feb 19 2018
    

Formula

E.g.f.: exp( Sum_{n>=0} 2*(2*n+1)^(2*n) * x^(2*n+1)/(2*n+1)! ).
a(n) = Sum_{k=0..n} -(-1)^k*C(n,k) * (k-1)^(k-1) * (n-k+1)^(n-k-1).
a(n) ~ c * n^(n-1), where c = (1-LambertW(exp(-1))^2)/LambertW(exp(-1)) = 3.31265693390754834... if n is even and c = (1+LambertW(exp(-1))^2)/ LambertW(exp(-1)) = 3.86958601942969593... if n is odd. - Vaclav Kotesovec, Nov 27 2012

A138909 Expansion of e.g.f.: (1+x)/(1-x*exp(x)).

Original entry on oeis.org

1, 2, 6, 33, 232, 2045, 21636, 267043, 3766848, 59776137, 1053986500, 20442543671, 432537117552, 9914571191005, 244742376434388, 6473030199939675, 182614314495736576, 5473825396372806545, 173728330742517310980
Offset: 0

Views

Author

Paul D. Hanna, Apr 05 2008, Apr 06 2008

Keywords

Comments

The n-th term of the n-th inverse binomial transform of this sequence equals n! for n>=0.

Examples

			If the successive inverse binomial transforms are placed in a table,
then we see that the diagonal consists of the factorials:
n=0:[(1),2,6,33,232,2045,21636,267043,3766848,59776137,1053986500,...];
n=1:[1,(1),3,20,129,1164,12265,151458,2136337,33901640,597761361,...];
n=2:[1,0,(2),13,64,693,6856,86175,1210896,19228825,339012304,...];
n=3:[1,-1,3,(6),25,482,3429,50908,678465,10937430,192150469,...];
n=4:[1,-2,6,-7,(24),381,844,36291,341728,6433865,107801436,...];
n=5:[1,-3,11,-32,97,(120),-839,37158,55953,4638052,54573025,...];
n=6:[1,-4,18,-75,304,-811,(720),40783,-262608,5542425,6069736,...];
n=7:[1,-5,27,-142,729,-3282,11941,(5040),-497279,9166130,...];
n=8:[1,-6,38,-239,1480,-8643,45844,-178557,(40320),12301705,...];
n=9:[1,-7,51,-372,2689,-18844,125289,-741974,3354513,(362880),...].
		

Crossrefs

Cf. A006153.
Cf. A138910 (inverse binomial transform); variants: A138911, A138737.

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[(1+x)/(1-x*Exp[x]),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jun 09 2018 *)
  • PARI
    {a(n)=local(A=[1]);for(k=1,n,A=concat(A,0); A[k+1]=k!-polcoeff(subst(Ser(A),x,x/(1+k*x+x*O(x^k)))/(1+k*x),k));A[n+1]}
    
  • PARI
    {a(n)=n!+sum(k=0,n-1,k!*binomial(n,k)*n*k^(n-k-1))}

Formula

E.g.f. (1+x)/(1-x*exp(x)) - Olivier Gérard, Sep 15 2016
O.g.f. satisfies: [x^n] A( x/(1+n*x) )/(1+n*x) = n! for n>=0.
E.g.f. satisfies: [x^n] A(x)*exp(-n*x) = 1 for n>=0.
a(n) = n! + Sum_{k=0..n-1} k!*C(n,k)*n*k^(n-k-1) for n>1 with a(0)=1.
Equivalent to the sum above by properties of the binomial triangle:
a(n) = A006153(n)+n*A006153(n-1).
a(n) = n! ( Sum_{k=0..n-1} ((n-1-k)^k + (n-k)^k)/k!) for n>1 with a(0)=1.
a(n) ~ n! / LambertW(1)^n. - Vaclav Kotesovec, Oct 30 2017

Extensions

Name change and e.g.f. by Olivier Gérard, Sep 15 2016
Showing 1-4 of 4 results.