login
A330729
Numbers k that are divisible by all integers less than or equal to the cube root of k.
0
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, 96, 108, 120, 180, 240, 300, 420
OFFSET
1,2
EXAMPLE
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).
MATHEMATICA
Select[Range[1000], Divisible[#, LCM @@ Range @ Floor @ Surd[#, 3]] &] (* Amiram Eldar, Dec 28 2019 *)
PROG
(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
(PARI) is(k) = {my(m=sqrtnint(k, 3)); sum(i=1, m, Mod(k, i)==0) == m; } \\ Jinyuan Wang, Dec 31 2019
CROSSREFS
Cf. A003102.
Sequence in context: A080750 A113768 A122936 * A118729 A008726 A302834
KEYWORD
nonn,fini,full
AUTHOR
Eric Fox, Dec 28 2019
STATUS
approved