%I #11 May 13 2022 18:25:02
%S 1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,1,
%T 1,0,1,1,1,0,1,0,1,0,0,1,1,0,1,0,1,0,1,0,1,0,1,1,1,0,1,1,0,0,1,0,1,0,
%U 1,0,1,0,1,1,0,0,1,0,1,0,0,1,1,0,1,1,1,0,1,0,1,0,1,1,1,0,1,0,0,0,1,0,1,0,0,1,1,0,1,0,1,0,1,0,1,0,0,1,1,0,1,1,1,0,1
%N a(n) = 1 if the number of divisors of n is not larger than 4, otherwise 0.
%H Antti Karttunen, <a href="/A353799/b353799.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F a(n) = [A000005(n) <= 4], where [ ] is the Iverson bracket.
%F a(n) = [A101296(n) <= 5].
%F For n > 1, a(n) = A302048(n) + A353788(n).
%t a[n_] := If[DivisorSigma[0, n] <= 4, 1, 0]; Array[a, 120] (* _Amiram Eldar_, May 13 2022 *)
%o (PARI) A353799(n) = (4>=numdiv(n));
%Y Characteristic function of A007964.
%Y Cf. A000005, A101296, A302048, A353788.
%K nonn
%O 1
%A _Antti Karttunen_, May 13 2022