OFFSET
0,2
COMMENTS
a(4) is too large to display. The number of decimal digits in (the number of decimal digits in a(4)) is approximately 64^64*log[10](64), that is, about 7.1*10^115. - Robert Israel, Jul 19 2016
LINKS
Wikipedia, Hyperoperation
FORMULA
a(n) = H_n(a(n-1),n), where H_n is the n-th hyperoperation.
EXAMPLE
a(0) = H_0(null,0) = 0+1 = 1.
a(1) = H_1(1,1) = 1+1 = 2.
a(2) = H_2(2,2) = 2*2 = 4.
a(3) = H_3(4,3) = 4^3 = 64.
a(4) = H_4(64,4) = 64^(64^(64^64)).
CROSSREFS
KEYWORD
nonn
AUTHOR
Tyler Skywalker, Jul 19 2016
STATUS
approved