OFFSET
1,2
COMMENTS
(1!^1!)!=1 -> 1 digit; (2!^2!)!=24 -> 2 digits; (3!^3!)!=veryverylargenumber -> 197573 digits; (4!^4!)!=?!...
From Jon E. Schoenfield, Dec 21 2008: (Start)
(3!^3!)! = (6^6)! = 46656! = 6.8964...*10^197572
(4!^4!)! = (24^24)! = 1333735776850284124449081472843776! = 1.1463...*10^43600856616158353989522412378215476. (End)
MATHEMATICA
a[n_]:=Length[IntegerDigits[(n!^n!)! ]];
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Vladimir Joseph Stephan Orlovsky, Dec 05 2008
EXTENSIONS
a(4) from Jon E. Schoenfield, Dec 21 2008
STATUS
approved