OFFSET
0,3
FORMULA
E.g.f.: 1 / (2 - BesselI(0,2*x) - BesselI(1,2*x)).
a(0) = 1; a(n) = Sum_{k=1..n} binomial(n,k) * A001405(k) * a(n-k).
MATHEMATICA
nmax = 20; CoefficientList[Series[1/(2 - BesselI[0, 2 x] - BesselI[1, 2 x]), {x, 0, nmax}], x] Range[0, nmax]!
a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, k] Binomial[k, Floor[k/2]] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 27 2019
STATUS
approved