A076686 a(n) = min(core(n),phi(n)) where core(n) is the squarefree part of n.

1, 1, 2, 1, 4, 2, 6, 2, 1, 4, 10, 3, 12, 6, 8, 1, 16, 2, 18, 5, 12, 10, 22, 6, 1, 12, 3, 7, 28, 8, 30, 2, 20, 16, 24, 1, 36, 18, 24, 10, 40, 12, 42, 11, 5, 22, 46, 3, 1, 2, 32, 13, 52, 6, 40, 14, 36, 28, 58, 15, 60, 30, 7, 1, 48, 20, 66, 17, 44, 24, 70, 2, 72, 36, 3, 19, 60, 24, 78, 5

Offset

1,3

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 = 0.239......

Mathematica

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

Prog

(PARI) a(n)=min(core(n), eulerphi(n))

Crossrefs

Cf. A000010, A007913, A076685.

Sequence in context: A375124 A322250 A175542 * A114810 A300718 A093819

Adjacent sequences: A076683 A076684 A076685 * A076687 A076688 A076689

Keyword

nonn

Author

Benoit Cloitre, Oct 25 2002

Status

approved