A139131 - OEIS

%I #6 Jun 06 2013 16:47:05

%S 1,3,6,10,15,21,14,6,15,55,66,78,91,105,30,34,51,57,190,210,231,253,

%T 138,30,65,39,42,406,435,465,62,66,561,595,210,222,703,741,390,410,

%U 861,903,946,330,345,1081,282,42,35,255,1326,1378,159,165,770,798,1653,1711

%N Squarefree kernel of n*(n+1)/2.

%C a(n) = A007947(A000217(n));

%C a(A014601(n)) = A078636(A014601(n));

%C a(n) = A078636(n) / A014695(n).

%H R. Zumkeller, <a href="/A139131/b139131.txt">Table of n, a(n) for n = 1..1000</a>

%t Times@@(Transpose[FactorInteger[#]][[1]])&/@Accumulate[Range[60]] (* _Harvey P. Dale_, Jun 06 2013 *)

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 10 2008