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 A114125 #20 Feb 16 2025 08:32:59
%S A114125 4,26,314,3595,40882,459577,5109839,56168169,611720495,6609454805,
%T A114125 70937808071,757060825018,8040423200947,85037651263063,
%U A114125 896113850117314,9413000361625346,98597629032410971,1030179406403917981,10739422018595513973,111729397883168684917,1160260967837159869621
%N A114125 a(n) is the 10^n-th semiprime.
%H A114125 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Semiprime.html">Semiprime.</a>
%t A114125 fQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; c = 0; k = 2; Do[While[c < 10^n, If[fQ@k, c++ ]; k++ ]; Print[k - 1], {n, 0, 8}]
%t A114125 (* checked by *) SemiPrimePi[n_] := Sum[ PrimePi[n/Prime@i] - i + 1, {i, PrimePi@ Sqrt@n}]
%o A114125 (Perl) use ntheory ":all"; print "$_ ",nth_semiprime(10**$_),"\n" for 0..15; # _Dana Jacobsen_, Oct 08 2018
%Y A114125 Cf. A001358, A006880, A006988, A066265, A078972.
%K A114125 nonn
%O A114125 0,1
%A A114125 _Robert G. Wilson v_, Feb 11 2006
%E A114125 a(14) from _Donovan Johnson_, Sep 27 2010
%E A114125 Corrected a(14), added a(15)-a(18) from _Dana Jacobsen_, Oct 10 2018
%E A114125 a(19)-a(20) from _Henri Lifchitz_, Nov 08 2024