OFFSET
1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{p prime, p == 3 (mod 4)} ((p-1)/(Product_{q prime, q <= p} q)) = 0.3662357207... . - Amiram Eldar, Jul 25 2022
MATHEMATICA
f[n_] := Module[{p = 2}, While[Divisible[n, p], p = NextPrime[p]]; p]; a[n_] := If[Mod[f[n], 4] == 3, 1, 0]; Array[a, 100] (* Amiram Eldar, Jul 25 2022 *)
PROG
CROSSREFS
Characteristic function of A353531.
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 24 2022
STATUS
approved