OFFSET
1,1
COMMENTS
This sequence is not the same as sequence A048109.
The asymptotic density of this sequence is A327839 - A059956 = 0.0799000375... - Amiram Eldar, Nov 01 2020
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
pow2Q[n_] := n == 2^IntegerExponent[n, 2]; aQ[n_] := ! SquareFreeQ[n] && pow2Q[DivisorSigma[0, n]]; Select[Range[640], aQ] (* Amiram Eldar, Sep 21 2019 *)
PROG
(PARI) isok(k) = my(d=numdiv(k)); !issquarefree(k) && (2^valuation(d, 2) == d); \\ Michel Marcus, Nov 20 2020
(Python)
from itertools import count, islice
from sympy import factorint
def A175496_gen(startvalue=2): # generator of terms >= startvalue
return filter(lambda n:max(f:=factorint(n).values())>1 and all(map(lambda m:not((k:=m+1)&-k)^k, f)), count(max(startvalue, 2)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, May 30 2010
EXTENSIONS
Extended by D. S. McNeil, May 31 2010
STATUS
approved