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A076685 a(n) = max(core(n),phi(n)) where core(n) is the squarefree part of n. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A066069 A019530 A019554 * A254503 A186646 A309108

Adjacent sequences:  A076682 A076683 A076684 * A076686 A076687 A076688

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Oct 25 2002

STATUS

approved

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Last modified November 30 15:27 EST 2020. Contains 338807 sequences. (Running on oeis4.)