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 A075570 #22 Feb 20 2024 07:01:28
%S A075570 4,9,8,15,14,27,10,21,16,25,6,35,12,49,18,55,24,65,32,39,20,33,26,45,
%T A075570 22,51,28,69,34,63,38,75,52,57,40,87,44,93,46,81,50,77,30,119,48,91,
%U A075570 36,95,42,85,54,125,56,111,62,105,58,99,64,115,66,133,60,121,70,123,68,129,82
%N A075570 Lexicographically earliest sequence of distinct composite numbers such that a(k) + a(k+1) is prime for all k.
%C A075570 Index of composite values: {1, 4, 3, 8, 7, 17, 5, 12, 9, 15, 2, 23, 6, 33, 10, 38, 14, 46, 20, 26, 11, 21, 16, 30, ...}. - _Michael De Vlieger_, Jul 18 2017
%H A075570 Michael De Vlieger, <a href="/A075570/b075570.txt">Table of n, a(n) for n = 1..3000</a>
%t A075570 a = {4}; Do[k = 2 - Boole@ EvenQ@ n; While[Nand[! MemberQ[a, k], CompositeQ@ k, PrimeQ[a[[n - 1]] + k]], k += 2]; AppendTo[a, k], {n, 2, 69}]; a (* _Michael De Vlieger_, Jul 18 2017 *)
%Y A075570 Cf. A025044, A072525, A085084, A240024.
%K A075570 nonn
%O A075570 1,1
%A A075570 _Amarnath Murthy_, Sep 25 2002
%E A075570 More terms from _David Wasserman_, Jan 20 2005
%E A075570 Definition clarified by _Peter Munn_, Jul 20 2017