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 A185999 #15 Jan 08 2025 10:41:16
%S A185999 291,24502749,36627829,3547310731,4721984179,461808766011
%N A185999 Automorphic semiprimes: semiprimes, sp, such that sp is the k-th semiprime and sp ends in k.
%C A185999 Analogy, this sequence is to semiprimes (A001358) as A046883 is to the primes (A000040) or as A035383 is to the squares (A000290) among many others.
%H A185999 <a href="/index/Ar#automorphic">Index entries for sequences related to automorphic numbers</a>
%t A185999 nextSemiPrime[n_] := Block[{k = n + 1}, While[ Plus @@ Last /@ FactorInteger@ k != 2, k++]; k]; c = 1; k = 4; lst = {}; While[k < 8100000000, If[ Mod[k, 10^Floor[1 + Log10@ c]] == c, AppendTo[lst, k]; Print[{c, k}]]; c++; k = nextSemiPrime@ k]; lst
%t A185999 These terms can be crosschecked by: SemiPrimePi[n_] := Sum[ PrimePi[n/Prime@ i] -i + 1, {i, PrimePi@ Sqrt@ n}]
%Y A185999 Cf. A001358, A046883, A046883, A186000.
%K A185999 hard,nonn,base
%O A185999 1,1
%A A185999 _Jonathan Vos Post_ & _Robert G. Wilson v_, Feb 24 2011
%E A185999 a(6) from _Donovan Johnson_, Mar 03 2011