OFFSET
1,2
COMMENTS
A006190(n) = Product_{k divides n} a(k), n >= 1.
FORMULA
MATHEMATICA
(* b = A006190 *) b[0] = 0; b[1] = 1; b[n_] := b[n] = 3*b[n-1] + b[n-2]; a[n_] := Product[b[d]^MoebiusMu[n/d], {d, Divisors[n]}]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Jan 20 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jan 19 2015
STATUS
approved