A189314 - OEIS

%I #15 Feb 03 2019 17:51:38

%S 1,4,8,52,82,128,136,142,172,178,192,214,232,262,292,304,332,346,352,

%T 382,388,412,448,472,478,484,500,502,542,556,586,592,604,622,632,640,

%U 652,676,712,724,752,766,772,802,808,832,838,841,862,864,916,922,934

%N Nonprimes k such that 2*omega(4k) = omega(4k+2), where omega(j) is the number of distinct primes dividing j, A001221.

%H Nathaniel Johnston, <a href="/A189314/b189314.txt">Table of n, a(n) for n = 1..10000</a>

%p Omega:=proc(n)return nops(factorset(n)):end:for n from 1 to 1000 do

%p if(not isprime(n) and 2*Omega(4*n)=Omega(4*n+2))then printf("%d, ",n);fi:od: # _Nathaniel Johnston_, Apr 19 2011

%t Select[Range[1000], ! PrimeQ[#] && 2*PrimeNu[4 #] == PrimeNu[4 # + 2] &] (* _T. D. Noe_, Apr 21 2011 *)

%Y Cf. A189313 (prime version of this sequence).

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Apr 19 2011