OFFSET
0,4
LINKS
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
FORMULA
a(n) = Sum_{k=0..n} (-k)^(n-k)*binomial(n,k)*Bell(k), where Bell() = A000110.
MAPLE
a:=series(exp(exp(x*exp(-x))-1), x=0, 25): seq(n!*coeff(a, x, n), n=0..24); # Paolo P. Lava, Mar 26 2019
MATHEMATICA
nmax = 24; CoefficientList[Series[Exp[Exp[x Exp[-x]] - 1], {x, 0, nmax}], x] Range[0, nmax]!
a[n_] := a[n] = Sum[(-k)^(n - k) Binomial[n, k] BellB[k], {k, n}]; a[0] = 1; Table[a[n], {n, 0, 24}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Jun 25 2018
STATUS
approved