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 A307341 #28 Nov 13 2024 16:34:11 %S A307341 16,24,36,40,54,56,60,81,84,88,90,100,104,126,132,135,136,140,150,152, %T A307341 156,184,189,196,198,204,220,225,228,232,234,248,250,260,276,294,296, %U A307341 297,306,308,315,328,340,342,344,348,350,351,364,372,375,376,380,414 %N A307341 Products of four primes, not all distinct. %C A307341 Numbers with exactly four prime factors (counted with multiplicity) but fewer than four distinct prime factors. %C A307341 Numbers n such that bigomega(n) = 4 and omega(n) < 4. %H A307341 Kalle Siukola, <a href="/A307341/b307341.txt">Table of n, a(n) for n = 1..10000</a> %o A307341 (Python) %o A307341 import sympy %o A307341 def bigomega(n): return sympy.primeomega(n) %o A307341 def omega(n): return len(sympy.primefactors(n)) %o A307341 print([n for n in range(1, 1000) if bigomega(n) == 4 and omega(n) < 4]) %o A307341 (PARI) isok(n) = (bigomega(n) == 4) && (omega(n) < 4); \\ _Michel Marcus_, Apr 03 2019 %Y A307341 Setwise difference of A014613 and A046386. %Y A307341 Union of A030514, A065036, A085986 and A085987. %K A307341 easy,nonn %O A307341 1,1 %A A307341 _Kalle Siukola_, Apr 02 2019