OFFSET
0,3
COMMENTS
a(5) > 10^(10^50).
FORMULA
a(n) = n!^a(n - 1) starting with a(0)=0!=1.
EXAMPLE
a(3) = 36 because 3!^(2!^(1!^0!)) = 36
MATHEMATICA
a[0] := 1 a[n_Integer] := n!^a[n - 1]
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jon Kongsvold (Jon.Kongsvold(AT)idi.ntnu.no), Aug 28 2002
EXTENSIONS
Edited by Henry Bottomley, Jul 13 2003
STATUS
approved