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 A075818 #24 Sep 08 2022 08:45:07 %S A075818 8,12,18,20,28,30,42,44,50,52,66,68,70,76,78,92,98,102,110,114,116, %T A075818 124,130,138,148,154,164,170,172,174,182,186,188,190,212,222,230,236, %U A075818 238,242,244,246,258,266,268,282,284,286,290,292,310,316,318,322,332,338 %N A075818 Even numbers with exactly 3 prime factors (counted with multiplicity). %C A075818 Twice the semiprime numbers. - _Juri-Stepan Gerasimov_, Jun 01 2010 %H A075818 Vincenzo Librandi, <a href="/A075818/b075818.txt">Table of n, a(n) for n = 1..2626</a> %F A075818 a(n)=2*A001358(n). - _Juri-Stepan Gerasimov_, Jun 01 2010 %e A075818 28=2^2*7, 30=2*3*5 and 42=2*3*7 are even and are products of exactly 3 primes. %p A075818 ts_bo3_sod := proc(n); if (numtheory[bigomega](n)=3 and type(n,even)='true') then RETURN(n); fi end: abo3sod := [seq(ts_bo3_sod(i), i=1..2300)]: abo3sod; %t A075818 Select[Range[100], Plus@@Last/@FactorInteger[#]==2&] 2 (* _Vincenzo Librandi_, Nov 10 2018 *) %t A075818 Select[Range[2,400,2],PrimeOmega[#]==3&] (* _Harvey P. Dale_, Oct 15 2021 *) %o A075818 (PARI) list(lim)=my(v=List()); forprime(p=2, lim\4, forprime(q=2, min(lim\p\2,p), listput(v, 2*p*q))); Set(v) \\ _Charles R Greathouse IV_, Aug 29 2017 %o A075818 (Magma) [2*n: n in [2..200] | &+[d[2]: d in Factorization(n)] eq 2]; // _Vincenzo Librandi_ Nov 10 2018 %Y A075818 Cf. A046470, A053858. %K A075818 easy,nonn %O A075818 1,1 %A A075818 _Jani Melik_, Oct 13 2002 %E A075818 Edited by _Dean Hickerson_, Oct 21 2002