A145109 a(n) = 2*n * core(2*n).

4, 4, 36, 16, 100, 36, 196, 16, 36, 100, 484, 144, 676, 196, 900, 64, 1156, 36, 1444, 400, 1764, 484, 2116, 144, 100, 676, 324, 784, 3364, 900, 3844, 64, 4356, 1156, 4900, 144, 5476, 1444, 6084, 400, 6724, 1764, 7396, 1936, 900, 2116, 8836, 576, 196, 100, 10404

Offset: 1

Author

Reikku Kulon, Oct 02 2008

Keywords

• easy
• nonn

Comments

All terms are even squares (A016742).

Links

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

Crossrefs

Cf. A007913, A016742, A053143.

Programs

Mathematica

a[1] = 4; a[n_] := 2*n * Times @@ (First[#]^Mod[Last[#], 2] & /@ FactorInteger[2*n]); Array[a, 50] (* Amiram Eldar, Sep 05 2020 *)

PARI

a(n) = 2*n * core(2*n); \\ Michel Marcus, Aug 09 2013

Formula

a(n) = A053143(2*n). - Michel Marcus, Aug 09 2013

Extensions

Definition corrected by Michel Marcus, Aug 09 2013