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 A115074 #20 Feb 11 2021 03:56:30 %S A115074 2,2,3,3,2,3,5,3,5,3,7,2,3,5,11,5,3,7,5,13,3,7,5,7,2,17,3,5,19,5,3,7, %T A115074 11,5,23,3,7,11,5,13,3,7,29,13,5,11,31,5,7,2,11,5,17,7,3,7,37,5,19,17, %U A115074 13,5,3,41,7,13,19,43,7,11,5,23,47,7,3,7,11,5,17,23,13,53,3,11,7,5,19,29,13 %N A115074 a(n) is the largest prime dividing the n-th nonsquarefree positive integer. %H A115074 Amiram Eldar, <a href="/A115074/b115074.txt">Table of n, a(n) for n = 1..10000</a> %F A115074 a(n) = A006530(A013929(n)). %e A115074 12, the 4th nonsquarefree positive integer, is 2^2 * 3. 3 is the largest prime dividing 12. So a(4) = 3. %p A115074 with(numtheory): a:=proc(n) if mobius(n)=0 then op(nops(factorset(n)),factorset(n)) fi end: seq(a(n),n=1..270); # _Emeric Deutsch_, Mar 06 2006 %t A115074 FactorInteger[ # ][[ -1, 1]] & /@ Select[ Range@235, !SquareFreeQ@# &] (* _Robert G. Wilson v_, Mar 09 2006 *) %Y A115074 Cf. A117183, A115090, A013929, A006530. %K A115074 nonn %O A115074 1,1 %A A115074 _Leroy Quet_, Mar 01 2006 %E A115074 More terms from _Emeric Deutsch_ and _Robert G. Wilson v_, Mar 06 2006