OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..13
FORMULA
a(1) = 1, a(2) = 9, a(n) = Product_{i = 1..n-1} a(i), n >= 3.
a(1) = 1, a(2) = 9, a(n) = A001019(2^(n-3)) = 9^(2^(n-3)), n >= 3.
a(1) = 1, a(2) = 9, a(3) = 9, a(n) = (a(n-1))^2, n >= 4.
a(n) = A011764(n-2), n > 2. - R. J. Mathar, Sep 20 2009
MATHEMATICA
a[1]:= 1; a[2]:= 9; a[n_]:= Product[a[j], {j, 1, n-1}]; Table[a[n], {n, 1, 12}] (* G. C. Greubel, Oct 19 2018 *)
PROG
(PARI) {a(n) = if(n==1, 1, if(n==2, 9, prod(j=1, n-1, a(j))))};
for(n=1, 10, print1(a(n), ", ")) \\ G. C. Greubel, Oct 19 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jaroslav Krizek, Sep 17 2009
STATUS
approved