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 A357741 #56 Oct 29 2022 04:42:53 %S A357741 4,6,9,21,33,129,159,3066835,3067195,3067255,3067615,3067745,3068045, %T A357741 44690978227,44690978647,44690978983,44690979529 %N A357741 Semiprimes k such that k is divisible by its index in the sequence of semiprimes. %C A357741 No further terms <= 8040423200947. - _Lucas A. Brown_, Oct 13 2022 %C A357741 Conjecture: a(18) > 10^17. - _Martin Ehrenstein_, Oct 28 2022 %H A357741 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/semiprimemods.py">semiprimemods.py</a> %F A357741 a(n) = A001358(A106125(n)) %e A357741 The 1st semiprime is 4, which is divisible by 1, so 4 is in the sequence. %e A357741 The 4th semiprime is 10, which is not divisible by 4, so 10 is not in the sequence. %e A357741 The 7th semiprime is 21, which is divisible by 7, so 21 is in the sequence. %Y A357741 Cf. A001358, A106125, A356764. %K A357741 nonn,hard,more %O A357741 1,1 %A A357741 _Lucas A. Brown_, Oct 13 2022