OFFSET
1,1
COMMENTS
Also, composites with an even number of divisors. - Juri-Stepan Gerasimov, Jul 17 2009
LINKS
Zak Seidov, Table of n, a(n) for n = 1..8671
FORMULA
MATHEMATICA
m=100; Complement[Range[0, m^2], Range[0, m]^2, Prime[Range[PrimePi[m^2]]]] (* Zak Seidov, Dec 12 2011*)
PROG
(Haskell)
a089229 n = a089229_list !! (n-1)
a089229_list = f a018252_list $ tail a000290_list where
f (u:us) vs'@(v:vs) = if u < v then u : f us vs' else f us vs
-- Reinhard Zumkeller, Jul 07 2014
(PARI) lista(nn) = for (n=1, nn, if (!issquare(n) && !isprime(n), print1(n, ", "))); \\ Michel Marcus, Jun 01 2015
(PARI) is(n)=!issquare(n) && !isprime(n) \\ Charles R Greathouse IV, Oct 19 2015
(Magma) [n: n in [1..200] | not IsSquare(n) and not IsPrime(n)]; // Vincenzo Librandi, Jun 14 2016
(Python)
from math import isqrt
from sympy import primepi
def A089229(n):
def f(x): return int(n+primepi(x)+isqrt(x))
m, k = n, f(n)
while m != k: m, k = k, f(k)
return m # Chai Wah Wu, Oct 12 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Dec 10 2003
STATUS
approved