Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #15 May 21 2024 14:14:36
%S 30,42,66,70,78,102,110,114,130,138,154,170,174,182,186,190,222,230,
%T 238,246,258,266,282,286,290,310,318,322,354,366,370,374,402,406,410,
%U 418,426,430,434,438,442,470,474,494,498,506,518,530,534,574,582,590
%N Squarefree even composite numbers with an odd number of prime factors.
%C Prime factors counted with multiplicity. - _Harvey P. Dale_, May 21 2024
%H Charles R Greathouse IV, <a href="/A053858/b053858.txt">Table of n, a(n) for n = 1..10000</a>
%e a(3)=66 because 66 is even and its prime divisors are 2, 3 and 11, an odd number.
%p ts_m2_sod := proc(n); if (numtheory[mobius](n)=-1 and isprime(n)='false' and type(n,even)='true') then RETURN(n); fi end: am2sod := [seq(ts_m2_sod(i), i=1..2500)]: am2sod;
%t Select[Range[2,602,2],CompositeQ[#]&&SquareFreeQ[#]&&OddQ[PrimeOmega[#]]&] (* _Harvey P. Dale_, May 21 2024 *)
%o (PARI) is(n,f=factor(n))=n%2==0 && #f[,2]>2 && vecmax(f[,2])==1 && (#f[,2])%2 \\ _Charles R Greathouse IV_, Aug 29 2017
%Y A075819 is a subsequence. Intersection of A026424, A039956, and A002808.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Mar 28 2000
%E Name corrected by _Charles R Greathouse IV_, Aug 29 2017