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 A073483 #15 Jul 13 2013 12:02:48 %S A073483 1,1,1,1,1,1,3,1,1,15,1,1,1,5,105,1,1155,1,1,1,35,15015,1,1,255255, %T A073483 385,1,5,1,4849845,1,5005,1,7,85085,111546435,1,1,3234846615,77,35,1, %U A073483 1616615,3,1,1,100280245065,1,385,1,3710369067405,1,1001 %N A073483 For the n-th squarefree number: the product of all primes greater than its smallest factor and less than its largest factor and not dividing it. %C A073483 a(n)=1 iff A073484(n)=0; a(A000040(n))=1, a(A006094(n))=1, a(A002110(n))=1. %H A073483 Reinhard Zumkeller, <a href="/A073483/b073483.txt">Table of n, a(n) for n = 1..1000</a> %F A073483 a(n) = A002110(A073482(n))/(A005117(n)*A002110(A073481(n))). %e A073483 The 69th squarefree number is 110=2*5*11, primes between 2 and 11, not dividing 110, are 3 and 7, therefore a(69)=21. %t A073483 ppg[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]]},Times@@Select[Prime[ Range[PrimePi[First[f]]+1,PrimePi[Last[f]]-1]],!MemberQ[f,#]&]]; ppg/@ Select[ Range[100],SquareFreeQ] (* _Harvey P. Dale_, Jan 16 2013 *) %o A073483 (Haskell) %o A073483 a073483 n = product $ filter ((> 0) . (mod m)) $ %o A073483 dropWhile (<= a020639 m) $ takeWhile (<= a006530 m) a000040_list %o A073483 where m = a005117 n %o A073483 -- _Reinhard Zumkeller_, Jan 15 2012 %Y A073483 Cf. A005117, A000040, A073484, A117214. %K A073483 nonn,nice %O A073483 1,7 %A A073483 _Reinhard Zumkeller_, Aug 03 2002 %E A073483 a(44) and a(49) corrected by _Reinhard Zumkeller_, Jan 14 2012 %E A073483 Definition clarified by _Harvey P. Dale_, Jan 16 2013