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 A156900 #12 Oct 30 2017 22:39:36
%S A156900 1,2,3,5,7,7,11,11,13,16,16,17,19,23,23,23,27,29,31,31,37,37,37,37,41,
%T A156900 41,41,43,43,47,47,53,53,59,59,59,59,61,64,67,67,67,71,71,71,73,79,79,
%U A156900 79,79,83,83,89,89,89,89,97,97,97,97,97,101,103,103,107,107,107,109,113
%N A156900 a(n) = the smallest prime power >= the n-th positive squarefree integer.
%C A156900 The first positive squarefree integer is considered to be 1 here.
%H A156900 Michael De Vlieger, <a href="/A156900/b156900.txt">Table of n, a(n) for n = 1..10000</a>
%t A156900 Block[{nn = 110, s}, s = Select[Range[nn], SquareFreeQ]; Map[If[# == 1, 1, SelectFirst[# + Range[0, # - 1], PrimePowerQ]] &, s]] (* _Michael De Vlieger_, Oct 30 2017 *)
%Y A156900 Cf. A081217, A156898, A156899, A005117, A000961.
%K A156900 nonn
%O A156900 1,2
%A A156900 _Leroy Quet_, Feb 17 2009
%E A156900 Extended by _D. S. McNeil_, Mar 23 2009