OFFSET
1,2
MAPLE
q:= n-> not isprime(n) and andmap(i-> i[2]<3, ifactors(n)[2]):
select(q, [$1..111])[]; # Alois P. Heinz, Nov 10 2024
MATHEMATICA
Select[Range[120], !PrimeQ[#] && Max[FactorInteger[#][[;; , 2]]] < 3 &] (* Amiram Eldar, Nov 10 2024 *)
PROG
(Python)
from sympy import primepi, mobius, integer_nthroot
def A377880(n):
def f(x): return int(n+x+primepi(x)-sum(mobius(k)*(x//k**3) for k in range(1, integer_nthroot(x, 3)[0]+1)))
m, k = n, f(n)
while m != k: m, k = k, f(k)
return m # Chai Wah Wu, Nov 13 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Sahil K. Das, Nov 10 2024
STATUS
approved