

A211670


Number of iterations (...f_4(f_3(f_2(n))))...) such that the result is < 2, where f_j(x):=x^(1/j).


7



0, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,4


COMMENTS

Different from A001069, but equal for n < 16.


LINKS

Table of n, a(n) for n=1..90.


FORMULA

a(2^(n!)) = a(2^((n1)!))+1, for n>1.
G.f.: g(x)= 1/(1x)*sum_{k=1..infinity} x^(2^(k!)). The explicit first terms of the g.f. are
g(x)=(x^2+x^4+x^64+x^16777216+...)/(1x).


EXAMPLE

a(n)=1, 2, 3, 4, 5 for n=2^(1!), 2^(2!), 2^(3!), 2^(4!), 2^(5!) =2, 4, 64, 16777216, 16777216^5.


CROSSREFS

Cf. A001069, A010096, A084558, A211662, A211664, A211666, A211668, A211669.
Sequence in context: A138902 A211668 A255270 * A036452 A285481 A282622
Adjacent sequences: A211667 A211668 A211669 * A211671 A211672 A211673


KEYWORD

base,nonn


AUTHOR

Hieronymus Fischer, Apr 30 2012


STATUS

approved



