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 A304457 #30 Aug 29 2021 05:17:51
%S A304457 9,15,87,49,235,403,1241,1383,1047,3341,4359,9663,11499,14163,5947,
%T A304457 11183,19103,45151,50943,31367,173747,306003,215021,191303,86663,
%U A304457 62797,362609,425405,346727,531247,676067,721311,793469,741899,1637447,2896177,311843,4477649,7702927,1208153
%N A304457 Least semiprime of a run of exactly n odd semiprimes.
%C A304457 Runs of semiprimes of the same parity: {4, 6}, {9}, {10, 14}, {15, 21}, {22}, {25}, {26}, {33}, {34}, {35}, {38}, {39}, {46}, {49, 51, 55, 57}, {58, 62}, {65, 69}, {74}, {77}, {82}, {85}, {86}, {87, 91, 93}, {94}, ....
%C A304457 a(108) = 85305236689; a(101-107), if any, should be > 116820000000. - _Zak Seidov_, Aug 26 2021
%H A304457 Silvester Resnik, <a href="/A304457/b304457.txt">Table of n, a(n) for n = 1..100</a>
%e A304457 a(1) = 9 since it is the first occurrence of a single odd semiprime;
%e A304457 a(2) = 15 since 15 is the first of two consecutive odd semiprimes in the sequence of semiprimes;
%e A304457 a(3) = 87 since 87 is the first of exactly three consecutive odd semiprimes;
%e A304457 a(4) = 49 since 49 is the first of exactly four consecutive odd semiprimes; etc.
%t A304457 SplitBy[ Select[ Range@ 100, PrimeOmega@# == 2 &], Mod[#, 2] &] (* to view the runs of semiprimes of the same parity *)
%Y A304457 Cf. A001358, A304456, A304458.
%K A304457 easy,nonn
%O A304457 1,1
%A A304457 _Zak Seidov_, _Silvester Resnik_ and _Robert G. Wilson v_, May 12 2018