

A181942


Floor(n/((log n) log log n))


3



7, 29, 8, 6, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 14, 14
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

2,1


COMMENTS

The function f(x) = x/((log x) log log x) has a minimum of ~ 5.2 at x ~ 9.39 and is increasing for larger x. The growth of this function is related to the growth of prime numbers. As a result, the function f is a relatively fast growing function with the property that the map p > nextprime(f^1(p)) = A181943(p) seems to have p > floor(f(p)) = A181942(p), or p>floor(f(p)/2)*2+1, as left inverse "almost everywhere"(?) on the primes. (The function x/(log x)^2 also has this property, but is not growing as fast.)
This is the "decoding function" of A181922: Repeated application to the nth element of that sequence successively yields the n preceding smaller primes, at least for n<= 1000.


LINKS

Table of n, a(n) for n=2..99.


PROG

(PARI) A181942(n)=n\(log(n)*log(log(n)))


CROSSREFS

Sequence in context: A193288 A050548 A261845 * A140447 A038934 A262285
Adjacent sequences: A181939 A181940 A181941 * A181943 A181944 A181945


KEYWORD

sign


AUTHOR

M. F. Hasler, Apr 03 2012


STATUS

approved



