OFFSET
1,4
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
FORMULA
a(n) = 2 - A008966(n). - Antti Karttunen, Nov 18 2017
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2 - 6/Pi^2 = 1 + A229099. - Amiram Eldar, Sep 26 2022
MATHEMATICA
Table[If[SquareFreeQ[n], 1, 2], {n, 100}] (* Harvey P. Dale, Jul 09 2014 *)
PROG
(MuPAD) func(2-abs(numlib::moebius(n)), n):
(PARI) A007424(n) = (2-issquarefree(n)); \\ Antti Karttunen, Nov 18 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved