OFFSET
1,1
COMMENTS
EXAMPLE
a(2) = 1 is the least number that is squarefree already at the "zeroth derivative".
52283 = 7^2 * 11 * 97 is not squarefree, and applying A003415 successively 1-6 times yields numbers 20230, 19431, 14250, 21175, 15345, 15189. Only the last one of these 15189 = 3*61*83 is squarefree, and there are no numbers < 52283 that would produce as long (6) finite chain of nonsquarefree numbers, thus a(2+6) = 52283.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Antti Karttunen, Oct 12 2019
STATUS
approved