%I A154110
%S A154110 9,387420489
%N A154110 The largest number that can be written with n characters, using positive 
               integers, exponentiation and the factorial function.
%D A154110 Daniel J. Velleman, Exponential vs. Factorial, Am. Math. Monthly, Vol. 
               113, No.8, pp.689-703, Oct 2006.
%e A154110 a(1) = 9, as we are writing in base 10. a(2) = 9^9 = 387420489, because 
               we write it with superscripting raher than a character for the exponentiation. 
               For n>2, Velleman proves that a(n+1) = a(n)!, so that, as shown in 
               the cited paper, a(5) = (9^9)!!! where the exponentiation is by superscripting, 
               there are no parentheses used and the b!! means (b!)!. The sequence 
               is infinite, but cannot be displayed in OEIS format after a(2).
%Y A154110 Sequence in context: A013850 A131678 A029983 this_sequence A028446 A058470 
               A058434
%Y A154110 Adjacent sequences: A154107 A154108 A154109 this_sequence A154111 A154112 
               A154113
%K A154110 base,bref,nonn
%O A154110 1,1
%A A154110 Jonathan Vos Post (jvospost3(AT)gmail.com), Jan 04 2009