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 A247558 #23 Apr 08 2024 06:54:32
%S A247558 4,6,10,15,25,26,35,38,39,57,58,62,65,86,87,91,94,95,121,122,123,134,
%T A247558 142,143,145,146,159,161,169,202,203,205,206,209,214,215,217,218,219,
%U A247558 221,262,265,278,299,301,302,303,305,309,326,327,329,335,341,346,361,362,365,382,386,393,394,395,398
%N A247558 Smallest integer x > 0 such that the number of semiprimes in the interval (x/2, x] equals n.
%C A247558 Analogous to A080359: the Labos Elemer primes.
%H A247558 Jens Kruse Andersen, <a href="/A247558/b247558.txt">Table of n, a(n) for n = 1..10000</a>
%e A247558 a(6) = 26 because in the interval, (13, 26], {14, 15, 21, 22, 25, 26} are six semiprimes.
%t A247558 SemiPrimeQ[n_] := PrimeOmega[n] == 2; mx = 1000; t = Table[0, {mx + 1}]; s = 0; Do[ If[ SemiPrimeQ[k], s++]; If[ SemiPrimeQ[k/2], s--]; If[s <= mx && t[[s + 1]] == 0, t[[s + 1]] = k], {k, 8*mx}]; Rest[t]
%Y A247558 Cf. A001358, A072000, A080359.
%K A247558 nonn
%O A247558 1,1
%A A247558 _Jonathan Vos Post_ and _Robert G. Wilson v_, Sep 19 2014