OFFSET
1,2
COMMENTS
Exponential double factorial.
The next term is too large to include.
EXAMPLE
a(1)=1;
a(2)=2;
a(3)=3^1=3;
a(4)=4^2=16;
a(5)=5^3=125;
a(6)=6^16=2821109907456;
etc.
MATHEMATICA
a[1]=1; a[2]=2; a[n_]:=n^a[n-2]; Array[a, 7] (* Stefano Spezia, Feb 14 2024 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paolo P. Lava and Giorgio Balzarotti, May 22 2008
STATUS
approved