OFFSET
1,2
COMMENTS
The unitary version of A085829.
FORMULA
Lim_{n->oo} a(n+1)/a(n) = exp(zeta(2)) = exp(Pi^2/6) = 5.180668... (since A064608(n) ~ n*log(n)/zeta(2)).
EXAMPLE
a(2) = 6 because the average number of unitary divisors of {1..6} is A064608(6)/6 = 13/6 > 2.
MATHEMATICA
seq={}; s = 0; k = 1; Do[While[s += 2^PrimeNu[k]; s < k*n, k++]; AppendTo[seq, k]; k++, {n, 1, 10}]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Oct 22 2019
STATUS
approved