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 1-5 of 5 results.

A362474 E.g.f. satisfies A(x) = exp(x + x^2/2 * A(x)^2).

Original entry on oeis.org

1, 1, 2, 10, 70, 646, 7576, 106744, 1761628, 33361948, 712950616, 16976294776, 445751093800, 12795850109992, 398697898011232, 13401365473319776, 483376669737381136, 18623161719254837008, 763300232417720682784, 33163224556779213475744
Offset: 0

Views

Author

Seiichi Manyama, Apr 21 2023

Keywords

Crossrefs

Column k=1 of A362483.

Programs

  • Mathematica
    nmax = 20; A[_] = 1;
    Do[A[x_] = Exp[x + x^2/2*A[x]^2] + O[x]^(nmax+1) // Normal, {nmax}];
    CoefficientList[A[x], x]*Range[0, nmax]! (* Jean-François Alcover, Mar 04 2024 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^2*exp(2*x))/2)))

Formula

E.g.f.: exp(x - LambertW(-x^2 * exp(2*x))/2) = sqrt(-LambertW(-x^2*exp(2*x))/x^2).
a(n) = n! * Sum_{k=0..floor(n/2)} (1/2)^k * (2*k+1)^(n-k-1) / (k! * (n-2*k)!).
a(n) ~ sqrt(1 + LambertW(exp(-1/2))) * n^(n-1) / (sqrt(2) * exp(n) * LambertW(exp(-1/2))^(n+1)). - Vaclav Kotesovec, Nov 10 2023

A362490 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j * (3*j+1)^(n-2*j-1) / (j! * (n-3*j)!).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 17, 1, 1, 1, 1, 4, 33, 161, 1, 1, 1, 1, 5, 49, 321, 1351, 1, 1, 1, 1, 6, 65, 481, 2841, 12391, 1, 1, 1, 1, 7, 81, 641, 4471, 31641, 153385, 1, 1, 1, 1, 8, 97, 801, 6241, 57751, 498849, 2388905, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 22 2023

Keywords

Examples

			Square array begins:
  1,    1,    1,    1,    1,    1,     1, ...
  1,    1,    1,    1,    1,    1,     1, ...
  1,    1,    1,    1,    1,    1,     1, ...
  1,    2,    3,    4,    5,    6,     7, ...
  1,   17,   33,   49,   65,   81,    97, ...
  1,  161,  321,  481,  641,  801,   961, ...
  1, 1351, 2841, 4471, 6241, 8151, 10201, ...
		

Crossrefs

Columns k=0..3 give A000012, A362477, A362478, A362479.
Cf. A362378.

Programs

  • PARI
    T(n, k) = n! * sum(j=0, n\3, (k/6)^j*(3*j+1)^(n-2*j-1)/(j!*(n-3*j)!));

Formula

E.g.f. A_k(x) of column k satisfies A_k(x) = exp(x + k*x^3/6 * A_k(x)^3).
A_k(x) = exp(x - LambertW(-k*x^3/2 * exp(3*x))/3).
A_k(x) = ( -2 * LambertW(-k*x^3/2 * exp(3*x))/(k*x^3) )^(1/3) for k > 0.

A362491 E.g.f. satisfies A(x) = exp(x + x^4/4 * A(x)^4).

Original entry on oeis.org

1, 1, 1, 1, 7, 151, 2251, 26251, 273841, 3281041, 61021801, 1518719401, 38199828151, 905801252071, 21398411003971, 560160675014851, 17260034904184801, 596005144436100001, 21359751419836426321, 773082506262449261521, 28839945213850125032551
Offset: 0

Views

Author

Seiichi Manyama, Apr 22 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^4*exp(4*x))/4)))

Formula

E.g.f.: exp(x - LambertW(-x^4 * exp(4*x))/4) = ( -LambertW(-x^4 * exp(4*x))/x^4 )^(1/4).
a(n) = n! * Sum_{k=0..floor(n/4)} (1/4)^k * (4*k+1)^(n-3*k-1) / (k! * (n-4*k)!).

A362390 E.g.f. satisfies A(x) = exp(x + x^3/3 * A(x)).

Original entry on oeis.org

1, 1, 1, 3, 17, 81, 441, 3641, 33825, 318753, 3505521, 45095601, 616484001, 9013086369, 145909533225, 2556431401161, 47388760825281, 937507626246081, 19840711661183457, 443937299529447009, 10456231167451597761, 259738234024404363201
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Crossrefs

Column k=2 of A362378.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3/3*exp(x)))))

Formula

E.g.f.: exp(x - LambertW(-x^3/3 * exp(x))) = -3 * LambertW(-x^3/3 * exp(x))/x^3.
a(n) = n! * Sum_{k=0..floor(n/3)} (1/3)^k * (k+1)^(n-2*k-1) / (k! * (n-3*k)!).

A362493 E.g.f. satisfies A(x) = exp(x - x^3/3 * A(x)^3).

Original entry on oeis.org

1, 1, 1, -1, -31, -319, -2279, -4199, 269473, 7155233, 114846641, 920526641, -18415853279, -1115017249631, -31675298017271, -526379460621559, 2394778195929281, 603748739138745281, 27895091311964499553, 769764386129113157473, 6164705700089328588481
Offset: 0

Views

Author

Seiichi Manyama, Apr 22 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(x^3*exp(3*x))/3)))

Formula

E.g.f.: exp(x - LambertW(x^3 * exp(3*x))/3) = ( LambertW(x^3 * exp(3*x))/x^3 )^(1/3).
a(n) = n! * Sum_{k=0..floor(n/3)} (-1/3)^k * (3*k+1)^(n-2*k-1) / (k! * (n-3*k)!).
Showing 1-5 of 5 results.