A086297 Squarefree kernels of 7-smooth numbers.

1, 2, 3, 2, 5, 6, 7, 2, 3, 10, 6, 14, 15, 2, 6, 10, 21, 6, 5, 3, 14, 30, 2, 35, 6, 10, 42, 15, 6, 7, 10, 6, 14, 30, 21, 2, 70, 6, 15, 10, 3, 42, 30, 6, 14, 10, 105, 6, 14, 30, 5, 42, 2, 15, 70, 6, 21, 30, 10, 6, 42, 35, 30, 21, 6, 14, 10, 210, 6, 14, 15, 30, 3, 35, 10, 42, 2

Offset

1,2

Comments

a(n) = A007947(A002473(n));

a(n) <= 210 = 7*5*3*2; range = A018336.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

f[n_] := If[Max[(p = FactorInteger[n][[;; , 1]])] <= 7, Times @@ p, 0]; Select[f /@ Range[300], # > 0 &] (* Amiram Eldar, Sep 06 2020 *)

Crossrefs

Cf. A002473, A007947, A018336.

Sequence in context: A208644 A162323 A165743 * A261969 A281495 A056554

Adjacent sequences: A086294 A086295 A086296 * A086298 A086299 A086300

Keyword

nonn

Author

Reinhard Zumkeller, Jul 15 2003

Status

approved