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 A064900 #23 Jan 09 2025 10:36:15
%S A064900 15,33,35,51,69,85,87,123,141,143,159,161,177,185,213,235,249,259,267,
%T A064900 303,321,323,335,339,393,411,447,485,501,519,533,535,537,553,573,591,
%U A064900 635,681,685,699,717,749,753,771,785,789,807,835,843,869,871,879,899
%N A064900 Semiprimes p1*p2 such that p2 > p1 and p2 mod p1 = 2.
%H A064900 John Cerkan, <a href="/A064900/b064900.txt">Table of n, a(n) for n = 1..10000</a>
%t A064900 okQ[n_] := Module[{p, e}, {p, e} = Transpose[FactorInteger[n]]; e == {1, 1} && Mod[p[[2]], p[[1]]] == 2]; Select[Range[1000], okQ]
%t A064900 Select[Range[1000],PrimeOmega[#]==2&&Mod[FactorInteger[#][[;;,1]][[2]],FactorInteger[#][[;;,1]][[1]]]==2&]//Quiet (* _Harvey P. Dale_, Jan 09 2025 *)
%o A064900 (PARI) isok(n) = (bigomega(n)==2) && (f=factor(n)) && (#f~ == 2) && ((f[2,1] % f[1,1]) == 2); \\ _Michel Marcus_, May 20 2017
%Y A064900 Cf. A001358 (p2 mod p1 = 0), A064899-A064911.
%K A064900 nonn
%O A064900 1,1
%A A064900 _Patrick De Geest_, Oct 13 2001
%E A064900 Name clarified by _Sean A. Irvine_, Jul 31 2023