A087005 - OEIS

%I #18 Feb 16 2025 08:32:50

%S 1,2,3,5,6,7,10,11,14,15,21,22,30,33,35,42,55,66,70,77,105,110,154,

%T 165,210,231,330,385,462,770,1155,2310

%N Divisors of 2310.

%C 2310 = 11# = A002110(5);

%C divisors of 2310 are squarefree (A005117) and 11-smooth;

%C a(A000005(2310)) = a(32) = 2310 is the last term.

%H <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Primorial.html">Primorial</a>

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Divisor.html">Divisor</a>

%t squarefrees[s_List] := Block[{a = Subsets[s]}, SortBy[Table[

%t Product[a[[n, m]], {m, 1, Length[a[[n]]]}], {n, 1, Length[a]}], Abs[#] &]]

%t A087005 = squarefrees[Prime[Range[5]]](* _Fred Daniel Kline_, Jan 25 2015 *)

%t Divisors[2310] (* _Harvey P. Dale_, Jun 27 2020 *)

%o (PARI) divisors(2310) \\ _Charles R Greathouse IV_, Jun 21 2017

%Y Cf. A018255, A018336, A087006, A087007, A087008.

%K nonn,fini,full,easy

%O 1,2

%A _Reinhard Zumkeller_, Jul 29 2003