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 A124941 #14 Dec 08 2024 06:54:38 %S A124941 36,56,84,100,132,136,152,228,340,344,372,376,472,484,488,532,546,564, %T A124941 568,580,621,632,686,708,770,804,808,820,846,852,856,868,872,950,1012, %U A124941 1192,1204,1206,1208,1274,1304,1326,1336,1444,1524,1550,1572,1576,1690 %N A124941 Numbers k such that k and k+4 are 4-almost primes. %H A124941 Charles R Greathouse IV, <a href="/A124941/b124941.txt">Table of n, a(n) for n = 1..10000</a> %e A124941 36=2^2*3^2, 40=2^3*5; 56=2^3*7, 60=2^2*3*5. %t A124941 Select[Range[1690], PrimeOmega[#]==PrimeOmega[#+4]==4 &] (* _James C. McMahon_, Dec 07 2024 *) %o A124941 (PARI) isok(n) = (bigomega(n) == 4) && (bigomega(n+4) == 4); \\ _Michel Marcus_, Oct 11 2013 %Y A124941 Cf. A014613, A124940, A124942, A157483, A180117. %K A124941 nonn %O A124941 1,1 %A A124941 _Zak Seidov_, Nov 13 2006