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 A350371 #13 Apr 30 2023 11:56:44 %S A350371 60,84,90,120,126,132,140,150,156,168,198,204,220,228,234,240,260,264, %T A350371 270,276,280,294,306,308,312,315,336,340,342,348,350,364,372,378,380, %U A350371 408,414,440,444,456,460,476,480,490,492,495,516,520,522,525,528,532,550,552,558 %N A350371 Numbers with exactly 4 semiprime divisors. %t A350371 q[n_] := DivisorSum[n, 1 &, PrimeOmega[#] == 2 &] == 4; Select[Range[600], q] (* _Amiram Eldar_, Dec 28 2021 *) %t A350371 spd4Q[n_]:=Count[Divisors[n],_?(PrimeOmega[#]==2&)]==4; Select[Range[600],spd4Q] (* _Harvey P. Dale_, Apr 30 2023 *) %o A350371 (PARI) isok(k) = sumdiv(k, d, bigomega(d)==2) == 4; \\ _Michel Marcus_, Dec 28 2021 %Y A350371 Numbers with exactly k semiprime divisors: A346041 (k=1), A345381 (k=2), A345382 (k=3), this sequence (k=4), A350372 (k=5), A350373 (k=6), A350374 (k=7), A350375 (k=8). %K A350371 nonn %O A350371 1,1 %A A350371 _Wesley Ivan Hurt_, Dec 27 2021