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 A319898 Number of digits of 2^^n. 1
 1, 1, 1, 1, 2, 5, 19729 (list; graph; refs; listen; history; text; internal format)
 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). LINKS Table of n, a(n) for n=-1..5. Wikipedia, Knuth's up-arrow notation Wikipedia, Tetration 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 Adjacent sequences: A319895 A319896 A319897 * A319899 A319900 A319901 KEYWORD nonn,base AUTHOR _Natan Arie Consigli_, Dec 15 2018 STATUS approved

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Last modified March 5 03:04 EST 2024. Contains 370537 sequences. (Running on oeis4.)