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 1-2 of 2 results.

A277457 E.g.f.: exp(2*x)/(1+LambertW(-x)).

Original entry on oeis.org

1, 3, 12, 71, 616, 7197, 105052, 1829291, 36922928, 846851993, 21744781684, 617832652527, 19242299657896, 651815827343189, 23857403245171724, 938247816632341043, 39455261828928309088, 1766645684585351990961, 83913998998426051745764, 4214295288128637488870327, 223120214856875472660345176
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 16 2016

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[Exp[2*x]/(1+LambertW[-x]), {x, 0, 20}], x]*Range[0, 20]!
    Table[1 + Sum[Binomial[n, m]*(1 + Sum[Binomial[m, k]*k^k, {k, 1, m}]), {m, 1, n}], {n, 0, 20}]
    Table[2^n + Sum[Binomial[n, k]*2^(n-k)*k^k, {k, 1, n}], {n, 0, 20}] (* Vaclav Kotesovec, Oct 28 2016 *)
  • PARI
    x='x+O('x^50); Vec(serlaplace(exp(2*x)/(1 + lambertw(-x)))) \\ G. C. Greubel, Nov 07 2017

Formula

a(n) ~ exp(2*exp(-1)) * n^n.

A294411 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. -exp(k*x)*LambertW(-x).

Original entry on oeis.org

0, 0, 1, 0, 1, 2, 0, 1, 4, 9, 0, 1, 6, 18, 64, 0, 1, 8, 33, 116, 625, 0, 1, 10, 54, 216, 1060, 7776, 0, 1, 12, 81, 388, 1865, 12702, 117649, 0, 1, 14, 114, 656, 3340, 21228, 187810, 2097152, 0, 1, 16, 153, 1044, 5905, 36414, 303765, 3296120, 43046721, 0, 1, 18, 198, 1576, 10100, 63480, 500374, 5222864, 66897288, 1000000000
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 30 2017

Keywords

Examples

			E.g.f. of column k: A_k(x) = x/1! + 2*(k + 1)*x^2/2! + 3*(k^2 + 2*k + 3)*x^3/3! + 4*(k^3 + 3*k^2 + 9*k + 16)*x^4/4! + ...
Square array begins:
    0,     0,     0,     0,     0,      0, ...
    1,     1,     1,     1,     1,      1, ...
    2,     4,     6,     8,    10,     12, ...
    9,    18,    33,    54,    81,    114, ...
   64,   116,   216,   388,   656,   1044, ...
  625,  1060,  1895,  3340,  5905,  10100, ...
		

Crossrefs

Columns k=0..2 give A000169, A277473, A277485.
Main diagonal gives A292633.
Cf. A290824.

Programs

  • Mathematica
    Table[Function[k, n! SeriesCoefficient[-Exp[k x] LambertW[-x], {x, 0, n}]][j - n], {j, 0, 10}, {n, 0, j}] // Flatten

Formula

E.g.f. of column k: -exp(k*x)*LambertW(-x).
Showing 1-2 of 2 results.