This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075819 #13 Mar 03 2021 04:19:47 %S A075819 30,42,66,70,78,102,110,114,130,138,154,170,174,182,186,190,222,230, %T A075819 238,246,258,266,282,286,290,310,318,322,354,366,370,374,402,406,410, %U A075819 418,426,430,434,438,442,470,474,494,498,506,518,530,534,574,582,590 %N A075819 Even squarefree numbers with exactly 3 prime factors. %C A075819 This sequence first differs from A053858 at 2310=2*3*5*7*11, which is in A053858 but not in this sequence. %H A075819 Charles R Greathouse IV, <a href="/A075819/b075819.txt">Table of n, a(n) for n = 1..10000</a> %F A075819 a(n) = 2 * A046388(n). - _Amiram Eldar_, Mar 03 2021 %e A075819 30=2*3*5 and 42=2*3*7 are even, squarefree and have 3 prime factors. %p A075819 ts_3_sod := proc(n); if (numtheory[bigomega](n)=3 and numtheory[mobius](n)=-1 and type(n,even)='true') then RETURN(n); fi end: a3sod := [seq(ts_3_sod(i), i=1..2500)]: a3sod; %t A075819 Select[2*Range[300],SquareFreeQ[#]&&PrimeNu[#]==3&] (* _Harvey P. Dale_, Feb 16 2018 *) %o A075819 (PARI) list(lim)=my(v=List()); forprime(p=5, lim\6, forprime(q=3, min(lim\(2*p),p-2), listput(v, 2*p*q))); Set(v) \\ _Charles R Greathouse IV_, Aug 29 2017 %Y A075819 Cf. A046388, A053858. %K A075819 easy,nonn %O A075819 1,1 %A A075819 _Jani Melik_, Oct 13 2002 %E A075819 Edited by _Dean Hickerson_, Oct 21 2002