OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = A030229(n)^2.
Sum_{n>=1} 1/a(n) = 21/(2*Pi^2). - Amiram Eldar, Jul 16 2020
MATHEMATICA
Select[Range[135], MoebiusMu[#] == 1 &]^2 (* Amiram Eldar, Jul 16 2020 *)
PROG
(PARI) is(n)=if(!issquare(n, &n), return(0)); my(f=factor(n)[, 2]); if(n>1, #f%2==0 && vecmax(f)==1, n==1) \\ Charles R Greathouse IV, Oct 16 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Nov 30 2002
STATUS
approved