OFFSET
1
LINKS
MATHEMATICA
f[1] = 1; f[n_] := Times @@ (NextPrime[#1]^#2 & @@@ FactorInteger[n]); a[n_] := Boole[DivisorSigma[1, n] <= 2*n < f[n]]; Array[a, 100] (* Amiram Eldar, Feb 22 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 22 2021
STATUS
approved