login
A319898
Number of digits of 2^^n.
1
1, 1, 1, 1, 2, 5, 19729
OFFSET
-1,5
COMMENTS
Next term is too large to fit in the data section.
2^^n is Don Knuth's up arrow notation for the power tower 2^2^...^2 (n times).
EXAMPLE
2^^-1=0, so a(-1)=1;
2^^0=1, so a(0)=1;
2^^1=2, so a(1)=1;
2^^2=4, so a(2)=1;
2^^3=16, so a(3)=2;
2^^4=65536, so a(4)=5.
CROSSREFS
Equals number of digits of A014221.
Sequence in context: A323338 A057678 A090071 * A325957 A247148 A139062
KEYWORD
nonn,base
AUTHOR
Natan Arie Consigli, Dec 15 2018
STATUS
approved