OFFSET
1,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
Florian Luca and Carl Pomerance, On the average number of divisors of the Euler function, Publicationes Mathematicae Debrecen, Vol. 70, No. 1-2 (2007), pp. 125-148.
FORMULA
Sum_{k=1..n} a(k) ~ n * exp(c(n) * (log(n)/log(log(n)))(1/2) * (1 + O(log(log(log(n)))/log(log(n))))), where c(n) is a number in the interval (1/7, 2*sqrt(2))*exp(-gamma/2) and gamma is A001620 (Luca and Pomerance, 2007). - Amiram Eldar, Oct 29 2022
EXAMPLE
Modulo 5, powers of 1,6,11 etc. are 1,1,1,1,1,1,...; of 2,7,12 etc. are 1,2,4,3,1,2,4,3,...; of 3,8,13 etc. are 1,3,4,2,1,3,4,2,...; of 4,9,14 etc. are 1,4,1,4,1,4,...; of 5,10,15 etc. are 1,0,0,0,0,... So the eventual period lengths are 1,4,4,2,1 giving three distinct lengths, so a(5)=3.
MAPLE
A066800 := proc(n)
numtheory[tau](numtheory[lambda](n)) ;
end proc:
seq(A066800(n), n=1..100) ; # R. J. Mathar, Oct 01 2017
MATHEMATICA
Array[DivisorSigma[0, CarmichaelLambda@ #] &, 103] (* Michael De Vlieger, Jul 16 2017 *)
PROG
(PARI)
A002322(n) = lcm(znstar(n)[2]); \\ This function from Charles R Greathouse IV, Aug 04 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Henry Bottomley, Dec 20 2001
EXTENSIONS
More terms from David Wasserman, Nov 14 2002
STATUS
approved