A076685 a(n) = max(core(n),phi(n)) where core(n) is the squarefree part of n.

1, 2, 3, 2, 5, 6, 7, 4, 6, 10, 11, 4, 13, 14, 15, 8, 17, 6, 19, 8, 21, 22, 23, 8, 20, 26, 18, 12, 29, 30, 31, 16, 33, 34, 35, 12, 37, 38, 39, 16, 41, 42, 43, 20, 24, 46, 47, 16, 42, 20, 51, 24, 53, 18, 55, 24, 57, 58, 59, 16, 61, 62, 36, 32, 65, 66, 67, 32, 69, 70, 71, 24, 73, 74

Offset

1,2

Links

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

Formula

Sum_{k=1..n} a(k) is asymptotic to c*n^2 with c = 0.3938......

Mathematica

core[n_] := Times @@ (First[#]^Mod[Last[#], 2]& /@ FactorInteger[n]); a[n_] := Max[EulerPhi[n], core[n]]; Array[a, 80] (* Amiram Eldar, Sep 03 2020 *)

Prog

(PARI) a(n)=if(n<1, 0, max(core(n), eulerphi(n)))

Crossrefs

Cf. A000010, A007913, A076686.

Sequence in context: A355263 A019554 A371573 * A254503 A186646 A309108

Adjacent sequences: A076682 A076683 A076684 * A076686 A076687 A076688

Keyword

nonn

Author

Benoit Cloitre, Oct 25 2002

Status

approved