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 A283919 #18 Nov 14 2020 09:45:41
%S A283919 4,4,9,4,4,9,4,4,25,9,4,4,4,4,4,9,4,49,25,4,9,4,4,9,4,4,4,25,4,4,9,4,
%T A283919 4,9,4,4,49,9,4,4,4,4,4,9,4,121,4,25,9,4,4,9,4,4,4,49,4,25,4,9,4,4,9,
%U A283919 4,4,169,9,4,25,4,4,4,4,9,4,4,9,4,4,9,4,4
%N A283919 The smallest square referenced in A013929 (Numbers that are not squarefree).
%H A283919 Amiram Eldar, <a href="/A283919/b283919.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Robert Price)
%e A283919 A013929(4) = 12, 12 = 2*2*3, so 12 is not squarefree, the square being 2*2 = 4.
%t A283919 s[n_] := If[(pos = Position[(f = FactorInteger[n])[[;; , 2]], _?(# >= 2 &)]) == {}, 1, f[[pos[[1, 1]], 1]]]; Select[Array[s, 250], # > 1 &]^2 (* _Amiram Eldar_, Nov 14 2020 *)
%o A283919 (PARI) f(n) = fordiv(n, d, if ((d>1) && issquare(d), return (d))); return (1);
%o A283919 apply(f, select(x->!issquarefree(x), [1..200])) \\ _Michel Marcus_, Nov 14 2020
%Y A283919 Cf. A013929, A046027.
%K A283919 nonn
%O A283919 1,1
%A A283919 _Robert Price_, Mar 17 2017