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 A175648 #26 Dec 09 2015 10:15:35 %S A175648 6,10,21,22,34,35,51,58,65,82,87,91,111,115,118,119,129,141,142,155, %T A175648 183,201,202,205,209,213,214,215,217,249,274,287,291,295,298,299,301, %U A175648 305,319,323,335,358,361,377,382,391,394,403,407,411,413,447,454,469,478 %N A175648 Semiprimes m such that m+4 is also semiprime. %H A175648 Zak Seidov, <a href="/A175648/b175648.txt">Table of n, a(n) for n = 1..10000</a> %p A175648 select(t -> numtheory:-bigomega(t)=2 and numtheory:-bigomega(t+4)=2, [$1..1000]); # _Robert Israel_, Feb 12 2015 %t A175648 Select[Range@ 480, And[PrimeOmega@ # == 2, PrimeOmega[# + 4] == 2] &] (* _Michael De Vlieger_, Dec 09 2015 *) %o A175648 (PARI) isok(n) = (bigomega(n) == 2) && (bigomega(n+4) == 2); \\ _Michel Marcus_, Feb 12 2015 %Y A175648 Cf. A001358, A001359, A175612. %K A175648 nonn,easy %O A175648 1,1 %A A175648 _Juri-Stepan Gerasimov_, Aug 02 2010 %E A175648 Corrected (309 removed) by _R. J. Mathar_, Aug 03 2010 %E A175648 Definition corrected by _Zak Seidov_, Feb 12 2015