A072058 Squarefree kernel of 2*prime(n)+1.

5, 7, 11, 15, 23, 3, 35, 39, 47, 59, 21, 15, 83, 87, 95, 107, 119, 123, 15, 143, 21, 159, 167, 179, 195, 203, 69, 215, 219, 227, 255, 263, 55, 93, 299, 303, 105, 327, 335, 347, 359, 33, 383, 129, 395, 399, 141, 447, 455, 51, 467, 479, 483, 503

Offset

1,1

Links

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

Formula

a(n) = A007947(A072055(n)).

Example

n = 12: 2*A000040(12)+1 = 2*37+1 = 75 and as A007947(75) = A007947(7*5*5) = 15: a(12) = 15.

Mathematica

rad[n_] := Times @@ FactorInteger[n][[;; , 1]]; rad /@ (2 * Select[Range[250], PrimeQ] + 1) (* Amiram Eldar, Sep 07 2020 *)

Crossrefs

Cf. A000040, A007947, A072055.

Sequence in context: A032699 A073088 A054059 * A072055 A314300 A189320

Adjacent sequences: A072055 A072056 A072057 * A072059 A072060 A072061

Keyword

nonn

Author

Reinhard Zumkeller, Jun 11 2002

Status

approved