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 1-8 of 8 results.

A380178 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of e.g.f. B(x)^k, where B(x) is the e.g.f. of A162659.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 3, 0, 1, 3, 8, 22, 0, 1, 4, 15, 62, 281, 0, 1, 5, 24, 126, 792, 5396, 0, 1, 6, 35, 220, 1641, 14922, 142297, 0, 1, 7, 48, 350, 2960, 30708, 384316, 4865806, 0, 1, 8, 63, 522, 4905, 55604, 777537, 12836406, 207407489, 0, 1, 9, 80, 742, 7656, 93300, 1393720, 25450806, 535396784, 10710044776, 0
Offset: 0

Views

Author

Seiichi Manyama, Feb 11 2025

Keywords

Examples

			Square array begins:
  1,      1,      1,      1,       1,       1,       1, ...
  0,      1,      2,      3,       4,       5,       6, ...
  0,      3,      8,     15,      24,      35,      48, ...
  0,     22,     62,    126,     220,     350,     522, ...
  0,    281,    792,   1641,    2960,    4905,    7656, ...
  0,   5396,  14922,  30708,   55604,   93300,  148446, ...
  0, 142297, 384316, 777537, 1393720, 2330305, 3716532, ...
		

Crossrefs

Columns k=0..1 give A000007, A162659.
Cf. A379168.

Programs

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

Formula

See A162659.

A162695 E.g.f. satisfies A(x) = exp( x*A(x) * exp(x*A(x)) ).

Original entry on oeis.org

1, 1, 5, 43, 549, 9341, 199303, 5122503, 154174121, 5321093689, 207228932811, 8991136486619, 430126003707997, 22494400020052533, 1276807091011902479, 78178242047074260751, 5136433584083525179857, 360458257425576984629873
Offset: 0

Views

Author

Paul D. Hanna, Jul 10 2009

Keywords

Examples

			E.g.f.: A(x) = 1 + x + 5*x^2/2! + 43*x^3/3! + 549*x^4/4! + 9341*x^5/5! +...
exp(x*A(x)) = 1 + x + 3*x^2/2! + 22*x^3/3! + 257*x^4/4! + 4136*x^5/5! +...
Log(A(x)) = x + 4*x^2/2! + 30*x^3/3! + 356*x^4/4! + 5780*x^5/5! +...;
compare log(A(x)) to the e.g.f. of A055779 given by:
x + 2*x^2/2! + 10*x^3/3! + 89*x^4/4! + 1156*x^5/5! +...
		

Crossrefs

Programs

  • Mathematica
    Flatten[{1,Table[Sum[Binomial[n,k] * (n+1)^(k-1) * k^(n-k),{k,0,n}],{n,1,20}]}] (* Vaclav Kotesovec, Jul 15 2014 *)
  • PARI
    a(n,m=1)=sum(k=0,n,binomial(n,k)*m*(n+m)^(k-1)*k^(n-k));
    
  • PARI
    /* Log(A(x)) = Sum_{n>=1} L(n)*x^n/n! where: */
    L(n)=if(n<1,0,sum(k=1,n,binomial(n,k)*n^(k-1)*k^(n-k)));

Formula

a(n) = Sum_{k=0..n} binomial(n,k) * (n+1)^(k-1) * k^(n-k).
Let A(x)^m = Sum_{n>=0} a(n,m)*x^n/n! with a(0,m)=1, then
a(n,m) = Sum_{k=0..n} binomial(n,k) * m*(n+m)^(k-1) * k^(n-k).
...
Let log(A(x)) = x*A(x)*exp(x*A(x)) = Sum_{n>=1} L(n)*x^n/n!, then
L(n) = Sum_{k=0..n} binomial(n,k) * n^(k-1) * k^(n-k) where
L(n) = n*A055779(n), where A055779(n) is the number of fat trees on n labeled vertices.
...
a(n) ~ s*sqrt((1+r*s)/(1+r*s*(3+r*s))) * n^(n-1) / (exp(n)*r^n), where r = 0.2222181377976171017... and s = 1.998622764215824983... are roots of the system of equations exp(r*s)*r*s*(1+r*s) = 1, exp(exp(r*s)*r*s) = s. - Vaclav Kotesovec, Jul 15 2014

A140049 E.g.f. A(x) satisfies: A( x*exp(-x*A(x)) ) = exp(x*A(x)).

Original entry on oeis.org

1, 1, 5, 55, 1005, 26601, 941863, 42372177, 2336926665, 153927536545, 11869936146891, 1055015092106889, 106731589524249517, 12163935655214359329, 1548324822731892094191, 218516875165035215308801, 33979477899236956531288977, 5790103152487972170694748097
Offset: 0

Views

Author

Paul D. Hanna, May 06 2008

Keywords

Examples

			A(x) = 1 + x + 5*x^2/2! + 55*x^3/3! + 1005*x^4/4! + 26601*x^5/5! +...
Log(A(x)) = G(x) = e.g.f. of A140055:
Log(A(x)) = x + 4*x^2/2! + 42*x^3/3! + 764*x^4/4! + 20400*x^5/5! +...
		

Crossrefs

Cf. A162659. [From Paul D. Hanna, Jul 09 2009]

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1/k, add(k*j
          *b(j-1, j)*b(n-j, k)*binomial(n-1, j-1), j=1..n))
        end:
    a:= n-> b(n, n+1):
    seq(a(n), n=0..20);  # Alois P. Heinz, Aug 21 2019
  • Mathematica
    m = 18; A[_] = 0;
    Do[A[x_] = Exp[x A[x] A[x A[x]]] + O[x]^m // Normal, {m}];
    CoefficientList[A[x], x] * Range[0, m-1]! (* Jean-François Alcover, Oct 03 2019 *)
  • PARI
    {a(n)=local(A=x);for(i=0,n,A=serreverse(x*exp(-A+x*O(x^n))));n!*polcoeff(A,n+1)}
    
  • PARI
    {a(n)=local(A=x);for(i=0,n,A=x*exp(subst(A,x,A+x*O(x^n))));n!*polcoeff(A,n+1)}
    From Paul D. Hanna, Jul 09 2009: (Start)
    
  • PARI
    {a(n,m=1)=if(n==0,1,if(m==0,0^n,sum(k=0,n,binomial(n,k)*m*(n+m)^(k-1)*a(n-k,k))))}
    
  • PARI
    /* Log(A(x)) = x*A(x*A(x)) = Sum_{n>=1} L(n)*x^n/n! where: */
    {L(n)=if(n<1,0,sum(k=1,n,binomial(n,k)*n^(k-1)*a(n-k,k)))} (End)

Formula

a(n) = A140054(n+1)/(n+1).
E.g.f.: A(x) = exp(G(x)) where G(x) = e.g.f. of A140055.
E.g.f. satisfies: A(x) = exp( x*A(x) * A(x*A(x)) ).
From Paul D. Hanna, Jul 09 2009: (Start)
E.g.f. satisfies: A(x) = exp(x*A(x)*A(x*A(x))).
...
Let A(x)^m = Sum_{n>=0} a(n,m)*x^n/n! with a(0,m)=1, then
a(n,m) = Sum_{k=0..n} C(n,k) * m*(n+m)^(k-1) * a(n-k,k).
...
Let log(A(x)) = x*A(x*A(x)) = Sum_{n>=1} L(n)*x^n/n!, then
L(n) = Sum_{k=1..n} C(n,k) * n^(k-1) * a(n-k,k).
(End)

A384719 E.g.f. A(x) satisfies A(x) = exp( x * A(x*A(x))^2 ).

Original entry on oeis.org

1, 1, 5, 61, 1281, 39641, 1655713, 88312869, 5792082817, 454510418545, 41802078248001, 4434246169988669, 535583662477158529, 72887981688629021097, 11079094119653898282337, 1867050981690536859738901, 346619463962928284995333377, 70501622878003227432547203809
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Crossrefs

Column k=1 of A384721.
Cf. A384691.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, (n-j+k)^(j-1)*binomial(n, j)*a(n-j, 2*j)));

Formula

See A384721.

A384720 E.g.f. A(x) satisfies A(x) = exp( x * A(x*A(x))^3 ).

Original entry on oeis.org

1, 1, 7, 118, 3385, 141556, 7918489, 561302470, 48589734337, 5001284972872, 599865865782481, 82534986682048066, 12863925185682542833, 2248009460254706256460, 436716594440553989797369, 93635975845903995553159126, 22021353830468757164023479169, 5650417076648052544704264390160
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Crossrefs

Column k=1 of A384722.

Programs

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

Formula

See A384722.

A384739 E.g.f. A(x) satisfies A(x) = exp( x * A(x*A(x)^2) ).

Original entry on oeis.org

1, 1, 3, 28, 461, 11776, 421207, 19832128, 1179482201, 85990657024, 7513043962571, 772836266189824, 92270347493126629, 12636256749099114496, 1965364897138717976735, 344225592620170387849216, 67392512492360201909759153, 14653181755453024592646111232, 3518079370651785227796264294163
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Crossrefs

Column k=1 of A384741.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, (2*n-2*j+k)^(j-1)*binomial(n, j)*a(n-j, j)));

Formula

See A384741.

A384740 E.g.f. A(x) satisfies A(x) = exp( x * A(x*A(x)^3) ).

Original entry on oeis.org

1, 1, 3, 34, 665, 20556, 901417, 52455250, 3885229665, 355223077336, 39166024398641, 5113078496932374, 778733373110049601, 136679150176555902436, 27360426865918664532393, 6191378995818235673842546, 1571577905668087973855557313, 444441393534829346316950781744
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Crossrefs

Column k=1 of A384742.
Cf. A384720.

Programs

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

Formula

See A384742.

A384757 E.g.f. A(x) satisfies A(x) = exp( -x * A(-x*A(x)) ).

Original entry on oeis.org

1, -1, -1, 14, 9, -1516, 4345, 507870, -4984063, -367545880, 7749976401, 471799390490, -18036953224367, -948817553760324, 60774529797257081, 2736041193224490494, -284790488755979731455, -10493764378757426300848, 1792499910367109444364961, 49177040508763120698604578
Offset: 0

Views

Author

Seiichi Manyama, Jun 09 2025

Keywords

Examples

			E.g.f.: A(x) = 1 - x - x^2/2 + 14*x^3/6 + 9*x^4/24 - 1516*x^5/120 + ...
A(-x*A(x)) =  1 + x - 3*x^2/2 - 11*x^3/6 + 233*x^4/24 + 621*x^5/120 - ...
		

Crossrefs

Column k=1 of A384758.

Programs

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

Formula

See A384758.
Showing 1-8 of 8 results.