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 A380069 #17 Feb 04 2025 19:29:48
%S A380069 33,217,793,4681,6697,9073,22177,58969,80137,96049,113401,132193,
%T A380069 197209,221761,289441,382537,470017,607609,671977,694153,935713,
%U A380069 1042417,1069993,1493857,1627921,1803601,1876393,2181961,2261953,2510569,2639737,2727649,3093697,3285361,3383353
%N A380069 Semiprime 12-gonal numbers.
%C A380069 All terms are odd.
%e A380069 33 = 3*11 is the product of 2 prime number and is a dodecagonal number = 3*(5*3-4).
%e A380069 217 = 7*31 is the product of 2 prime number and is a dodecagonal number = 7*(5*7-4).
%e A380069 793 = 13*61 is the product of 2 prime number and is a dodecagonal number = 13*(5*13-4).
%t A380069 Table[k*(5*k-4), {k, Select[Range[850], And @@ PrimeQ[{#, 5*#-4}] &]}] (* _Amiram Eldar_, Jan 11 2025 *)
%o A380069 (PARI) select(x->bigomega(x)==2, vector(1000, n, n*(5*n-4))) \\ _Michel Marcus_, Jan 20 2025
%Y A380069 Intersection of A001358 and A051624.
%Y A380069 Cf. A000384.
%K A380069 nonn
%O A380069 1,1
%A A380069 _Massimo Kofler_, Jan 11 2025