OFFSET
1,5
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge, 2003, p. 100
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
a(n) is asymptotic to (6K/Pi^2)*n/sqrt(log(n)) where K is the Landau-Ramanujan constant (A064533).
MATHEMATICA
Accumulate[Table[Boole[n > 1 && SquareFreeQ[n] && AllTrue[FactorInteger[n][[;; , 1]], Mod[#, 4] < 3 &]], {n, 1, 100}] ] (* Amiram Eldar, May 08 2022 *)
PROG
(PARI) a(n)=sum(i=1, n, issquarefree(i)*if(sum(u=1, i, sum(v=1, u, if(u^2+v^2-i, 0, 1))), 1, 0))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 18 2004
STATUS
approved