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 A128040 #10 Aug 18 2015 00:06:04 %S A128040 1,2,6,30,30,210,210,2310,30030,30030,30030,510510,9699690,9699690, %T A128040 9699690,223092870,223092870,6469693230,6469693230,200560490130, %U A128040 200560490130,200560490130,200560490130,7420738134810,7420738134810 %N A128040 a(n) = product of the primes which are <= the n-th squarefree positive integer. a(n) also is the LCM of the first n squarefree positive integers. %p A128040 A005117 := proc(n) option remember; local a; if n =1 then 1; else a := A005117(n-1)+1 ; while not numtheory[issqrfree](a) do a := a+1 ; od: RETURN(a) ; fi ; end: A128040 := proc(n) lcm( seq(A005117(i),i=1..n) ) ; end: seq(A128040(n),n=1..30) ; # _R. J. Mathar_, Nov 01 2007 %Y A128040 Cf. A034386, A005117. %K A128040 nonn %O A128040 1,2 %A A128040 _Leroy Quet_, May 07 2007 %E A128040 More terms from _R. J. Mathar_, Nov 01 2007