OFFSET
1,1
LINKS
John Cerkan, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1)=8 as 8=2*2*2, that is 8 is a composite integer and having 3 (an odd number) prime factors.
MATHEMATICA
fQ[n_] := Block[{p = Plus @@ Last /@ FactorInteger@n}, OddQ[p] && p > 1]; Select[ Range@200, fQ[ # ] &] (* Robert G. Wilson v, Jan 04 2006 *)
Select[Range[200], CompositeQ[#]&&OddQ[PrimeOmega[#]]&] (* Harvey P. Dale, Oct 14 2019 *)
PROG
(PARI) is(n)=!isprime(n) && bigomega(n)%2 \\ Charles R Greathouse IV, Sep 17 2015
(Python)
from math import isqrt, prod
from sympy import primerange, integer_nthroot, primepi
from oeis_sequences.OEISsequences import bisection
def A046339(n):
def g(x, a, b, c, m): yield from (((d, ) for d in enumerate(primerange(b, isqrt(x//c)+1), a)) if m==2 else (((a2, b2), )+d for a2, b2 in enumerate(primerange(b, integer_nthroot(x//c, m)[0]+1), a) for d in g(x, a2, b2, c*b2, m-1)))
def f(x): return int(n+1+primepi(x)+sum(sum(primepi(x//prod(c[1] for c in a))-a[-1][0] for a in g(x, 0, 1, 1, m)) for m in range(2, x.bit_length()+1, 2)))
return bisection(f, n, n) # Chai Wah Wu, Dec 19 2025
CROSSREFS
KEYWORD
nonn
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved
