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 A073250 #11 Feb 27 2023 14:54:41
%S A073250 14,21,38,57,65,69,77,105,110,114,118,122,129,133,145,154,158,165,177,
%T A073250 182,194,205,209,221,230,237,246,258,273,290,298,309,318,326,329,334,
%U A073250 345,354,357,365,370,381,385,390,398,402,406,410,417,426,429,434,437
%N A073250 Nonprime squarefree numbers n such that n+1 is also squarefree and nonprime, but not n-1 and n+2.
%H A073250 Harvey P. Dale, <a href="/A073250/b073250.txt">Table of n, a(n) for n = 1..1000</a>
%t A073250 tQ[n_]:=!PrimeQ[n+1]&&SquareFreeQ[n+1]&&(PrimeQ[n-1]||!SquareFreeQ[n-1])&&(PrimeQ[n+2]||!SquareFreeQ[n+2])
%t A073250 Select[Select[Complement[Range[500],Prime[Range[PrimePi[500]]]],SquareFreeQ],tQ] (* _Harvey P. Dale_, Feb 14 2011 *)
%t A073250 SequencePosition[Table[If[SquareFreeQ[n]&&!PrimeQ[n],1,0],{n,500}],{0,1,1,0}][[;;,1]]+1 (* _Harvey P. Dale_, Feb 27 2023 *)
%Y A073250 Cf. A000469, A005117, A073248, A073251, A073249.
%K A073250 nonn
%O A073250 1,1
%A A073250 _Reinhard Zumkeller_, Jul 22 2002