A330729 - OEIS

%I #21 Jan 21 2022 03:43:59

%S 1,2,3,4,5,6,7,8,10,12,14,16,18,20,22,24,26,30,36,42,48,54,60,72,84,

%T 96,108,120,180,240,300,420

%N Numbers k that are divisible by all integers less than or equal to the cube root of k.

%e 42 appears because the cube root of 42 is approximately 3.48 and 42 is divisible by 3, 2, and 1 (all positive integers less than 3.48).

%t Select[Range[1000], Divisible[#, LCM @@ Range @ Floor @ Surd[#, 3]] &] (* _Amiram Eldar_, Dec 28 2019 *)

%o (Magma) [k: k in [1..500]|forall{m:m in [1..Floor(k^(1/3))]|k mod m eq 0}]; // _Marius A. Burtea_, Dec 31 2019

%o (PARI) is(k) = {my(m=sqrtnint(k, 3)); sum(i=1, m, Mod(k, i)==0) == m; } \\ _Jinyuan Wang_, Dec 31 2019

%Y Cf. A003102.

%K nonn,fini,full

%O 1,2

%A _Eric Fox_, Dec 28 2019