OFFSET
1,3
COMMENTS
The asymptotic density of this sequence is 8/Pi^2 (A217739). - Amiram Eldar, Sep 26 2023
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = (A039956(n) - 2)/4, n >= 1.
MATHEMATICA
(# - 2)/4 & /@ Select[2 Range@ 202, SquareFreeQ] (* Michael De Vlieger, Dec 23 2015 *)
PROG
(PARI) lista(max) = forstep(k = 2, 4*max+2, 2, if(issquarefree(k), print1((k-2)/4, ", "))); \\ Amiram Eldar, Sep 26 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Dec 23 2015
STATUS
approved