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 A328661 #13 Jul 11 2022 02:39:02 %S A328661 1,2,3,1,5,2,7,3,1,5,11,2,13,7,3,1,17,5,19,11,2,13,23,7,3,1,17,5,29, %T A328661 19,31,11,2,13,23,7,37,3,1,17,41,5,43,29,19,31,47,11,2,13,23,7,53,37, %U A328661 3,1,17,41,59,5,61,43,29,19,31,47,67,11,2,13,71,23,73 %N A328661 If n is the k-th composite number then a(n) = a(k), otherwise a(n) = n. %H A328661 Rémy Sigrist, <a href="/A328661/b328661.txt">Table of n, a(n) for n = 1..10000</a> %F A328661 a(n) = 1 iff n belongs to A006508. %e A328661 a(42) = a(28) = a(18) = a(10) = a(5) = 5. %o A328661 (PARI) k=0; for (n=1, #a=vector(73), print1 (a[n] = if (bigomega(n)>1, a[k++], n) ", ")) %Y A328661 See A288469 and A328018 for similar sequences. %Y A328661 Cf. A002808, A006508. %K A328661 nonn %O A328661 1,2 %A A328661 _Rémy Sigrist_, Oct 24 2019