OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
E.g.f.: exp(x)+2*exp(2*x)*(BesselI(1,2*x)*(x-1)+x*BesselI(0,2*x)).
a(n) ~ sqrt(n)*4^n/sqrt(Pi). - Vaclav Kotesovec, Feb 14 2014
MAPLE
a:= proc(n) option remember; `if`(n<3, [1, 1, 5][n+1],
(n*(15*n^3-44*n^2+43*n-18) *a(n-1)
-2*(n-1)*(2*n-3)*(3*n^2-n+2) *a(n-2))/
((n-2)*(n+1)*(3*n^2-7*n+6)))
end:
seq(a(n), n=0..30);
MATHEMATICA
a[n_] := Module[{m}, If[n == 0, 1, InterpolatingPolynomial[Table[{k, If[k == n-1, n, 1]}, {k, 0, n-1}], m] /. m -> 2n]];
a /@ Range[0, 30] (* Jean-François Alcover, Dec 22 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 10 2014
STATUS
approved