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 A106127 #33 Oct 16 2022 03:21:51
%S A106127 1,2,4,39,51,52,71,6920,613377,613381,613405,613433,613437,613449,
%T A106127 613455,613536,613537,613548,613557,613569,613581,613583,613587,
%U A106127 613588,613608,613613,58155550,58155570,6384425447,6384425465,6384425505,6384425531,6384425567
%N A106127 Numbers k such that k-th semiprime == 2 (mod k).
%C A106127 No more terms through 160788536. - _Ryan Propper_, May 09 2006
%C A106127 a(34) > 10^12. - _Lucas A. Brown_, Oct 17 2020
%H A106127 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/semiprimemods.py">semiprimemods.py</a>
%e A106127 a(3)=4 is a term because the 4th semiprime (i.e., 10) == 2 (mod 4).
%t A106127 SemiprimeQ[n_] := (Plus @@ Last /@ FactorInteger[n] == 2); i = 0; Do[If[SemiprimeQ[n], i++; If[Mod[n, i] == 2, Print[i]]], {n, 10^9}] (* _Ryan Propper_, May 09 2006 *)
%Y A106127 Cf. A001358, A356755.
%K A106127 hard,nonn
%O A106127 1,2
%A A106127 _Shyam Sunder Gupta_, May 07 2005
%E A106127 More terms from _Ryan Propper_, May 09 2006
%E A106127 a(1), a(2), and a(29)-a(33) from _Lucas A. Brown_, Oct 17 2020